5 ms·

If you are a pilot and can't handle GPS dropping out, or the failure of any other single navigation aid, you should not be flying.

toomuchtodo 3mo ago
Highly dependent on weather and the complexity of the approach. Clear skies and VFR? I would agree. Heavy weather and an instrument approach or confounding factors? Not accurate imho. > At midnight on May 14, eight minutes after Clark and Kawsara took off from Roswell, they told Albuquerque Center that they’d lost their GPS. Unable to navigate on their own, they asked that the controller give them a heading—a magnetic direction to fly in. The controller gave them a heading to fly west, and then, a minute later, to turn north. > The pilots said that they wanted to fly an RNAV approach to Ruidoso. This being ruled out while GPS is jammed, the King Air pilots changed their request and asked to use an alternate form of landing system called Instrument Landing System, or ILS, that doesn’t require GPS reception. At 12:05 am, the controller assured the King Air that they would provide them with vectors to guide them “in a couple of minutes.” In the meantime, they kept flying north. > In retrospect, tragedy might have been avoided if Albuquerque air traffic control had been able to pay closer attention to the young pilots in the King Air. But tonight they were busy. Three other aircraft also reported that they’d lost their GPS and needed help. One was struggling to get a bearing on a radio beacon. > As they turned and descended toward Ruidoso’s lights, what the pilots couldn’t see was the 10,000-foot-high mass of the Capitan Mountains lying across their path. As they drew closer, the dark mass of rock appeared to rise up, swiping away the lights of the valley. This could have created "confusion and a loss of situational awareness,” Browne says. “When those lights go out, man, you know you are in big trouble.” Potentially low time pilots with degraded navigation aids at night (midnight) got behind the plane in an area with terrain, along with a high workload ATC not able to provide assistance more rapidly. (disclaimer: have a private license)
- 27183 3mo ago
  > Heavy weather and an instrument approach or confounding factors? Not accurate imho. Then what are you supposed to do when your GPS craps out on approach in low visibility and heavy weather? Obviously the answer is "fly the airplane". Which means you look at your artificial horizon, set trim and power for max climb, get to a safe altitude and figure it out. If you're paying attention you already have your chart folded to the airport you're landing at, so it shouldn't be too hard to orient yourself and figure out what's next. Either you'll be making another attempt at this airport without GPS or you'll be going somewhere else. There's never an excuse for failing to fly the airplane. That's basic airmanship. You need to be able to do it regardless of whether your GPS is working.
  - toomuchtodo 3mo ago
    It's very easy to write this comment when you're not the one getting behind the plane in the middle of the night with multiple simultaneous challenges (speaking from experience; I can feel the anxiety writing this comment from similar "white knuckle" experience), and I agree, keep flying the plane. Systems fail, that is the point of investigating incidents to improve systems. Humans are always the weakest link. I agree that an experienced pilot should be able to safely land on an approach assuming a loss of GPS. (General aviation (GA) is significantly less safe than commercial air travel, tracking at roughly 1.0 to 1.1 fatal accidents per 100,000 flight hours. Statistically, GA's per-hour fatality rate is about 14 times higher than driving a car, carrying a risk profile comparable to riding a motorcycle) Edit: My hot take is more communication and training needs to go into "As the pilot, you should be prepared to lose GPS at any time at critical moments in the flight lifecycle." Are we letting folks fly in potentially adverse conditions leaning too heavily on GPS leading to potentially avoidable accidents? I don't know, the NTSB is likely better informed to say so or not. If I was a flight instructor, I'd probably include loss of GPS during instrument approach at night and/or in weather as an experience to cover.
    - 27183 3mo ago
      I've been in this situation too. But I was trained for it and had a mental checklist to follow. I never had a GPS, though. It seems from the details of the article, which you rightly highlighted, that the pilots were using their GPS as a crutch and had no ability to fall back on basic dead reckoning. It seems they didn't know where they were. That's pretty inexcusable, like embarrassing even. I don't fly anymore, but I see similar behaviors developing on the water. People who use chartplotters for navigation don't have a very good understanding of what's going on around them. If you're just interactively following a computed lay line or a plotted course you don't really need to know what the currents are doing. You don't need to know what the hazards are. You're not actively engaged in navigating the boat.
    - SoftTalker 3mo ago
      > General aviation (GA) is significantly less safe than commercial air travel Since I've been paying attention from the peanut gallery, watching Blancolirio videos, etc. I would never fly on a small private plane. Seems like once a week there is a crash of a small GA craft somewhere, often with fatalities, due to loss of control (i.e. nothing wrong with the aircraft). Pilots seem to become overconfident or complacent, make bad decisions instead of "gettimg out the credit card and booking a hotel" as Juan likes to say -- if you can afford to fly your own plane you can afford a night at a hotel. They can't handle loss of visual flight conditions. They don't recognize when they need to ignore their inner ear and trust the instruments. They can't recover from stalls or upsets (and actual practice isn't required, because that too caused a lot of crashes). Worse, they often take family and friends with them. There's a reason a lot of life insurance policies specifically carve out private aircraft operation or travel as an exception to coverage.
- justinhj 3mo ago
  They deferred navigation to ATC instead of using their own capabilities such as VOR.
  - toomuchtodo 3mo ago
    They requested navigation assistance ATC could not promptly provide. I strongly agree the pilot in command could've done better, but if ATC was overloaded, they should've promptly communicated that to manage expectations that immediate help was not forthcoming. An aircraft covers a lot of ground "in a couple of minutes." (assuming ~120-200 knots) https://www.airresearch.com/Pilots/AIM-08/Chap6/aim0602.html https://www.airresearch.com/Pilots/AIM-08/Chap6/aim0602.html > a. Radar equipped ATC facilities can provide radar assistance and navigation service (vectors) to VFR aircraft in difficulty when the pilot can talk with the controller, and the aircraft is within radar coverage. Pilots should clearly understand that authorization to proceed in accordance with such radar navigational assistance does not constitute authorization for the pilot to violate CFRs. In effect, assistance is provided on the basis that navigational guidance information is advisory in nature, and the responsibility for flying the aircraft safely remains with the pilot. Potentially tangentially related to an overloaded and understaffed US ATC network, similar to the overloaded controller that led to the LaGuardia runway incursion on March 22, 2026. https://www.pilotsofamerica.com/community/threads/crj-collides-into-fire-engine-on-runway-at-la-guardia-3-22-26.153779/ https://www.pilotsofamerica.com/community/threads/crj-collid... ("What’s the bet that the controller had been overworked and the cab was understaffed? Seems to be an incredibly common thread lately.") American aviation is near collapse? - https://news.ycombinator.com/item?id=47494469 https://news.ycombinator.com/item?id=47494469 - March 2026 (106 comments) LaGuardia pilots raised safety alarms months before deadly runway crash - https://news.ycombinator.com/item?id=47503965 https://news.ycombinator.com/item?id=47503965 - March 2026 (310 comments) Two pilots dead after plane and ground vehicle collide at LaGuardia - https://news.ycombinator.com/item?id=47486386 https://news.ycombinator.com/item?id=47486386 - March 2026 (667 comments) https://news.ycombinator.com/item?id=47494936 https://news.ycombinator.com/item?id=47494936 (my comment with citations on this thesis) (my flavor of autism includes aggressive pattern matching)
    - wafflemaker 3mo ago
- trollbridge 3mo ago
  GPS is not, and never will be, reliable enough for IFR on its own. Relying on a tower in instrument conditions because GPS failed is unacceptable, because every other GPS user is in the same boat. If you’re flying IFR, you should have a working set of instruments and be using them. Why didn’t these pilots have their VORs tuned in for positioning?
  - toomuchtodo 3mo ago
    > GPS is not, and never will be, reliable enough for IFR on its own. WAAS GPS (~7.6M accuracy) is reliable enough for IFR on its own that many approaches have removed legacy RF ILS equipment for instrument approaches (RNAV LPV with synthetic glidescope from GNSS). I would agree this does not apply to the vast majority of general aviation (although certified receivers supporting this are well within the reach of GA at ~$6k), but facts and specifics are important, so enumerating that GPS and these trimmings make it designed to replace traditional IFR equipment under certain circumstances. WAAS is not a paid service, the additional precision is free if your receiver and autopilot supports it. Further reading: https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/approaches https://www.faa.gov/about/office_org/headquarters_offices/at... https://www.aopa.org/news-and-media/all-news/2025/october/pilot/instrument-tip-gps-substitute-or-alternate https://www.aopa.org/news-and-media/all-news/2025/october/pi... ("Today most IFR pilots use GPS as a primary source of navigation, whether they’re flying a departure, airway, or arrival defined by VORs; or segments of approaches based on navaids or that require DME or ADF.") [My note: This is straight from the advocacy group for general aviation in the US, AOPA.] https://www.flyingmag.com/everything-you-need-to-know-about-rnav-gps-approaches/ https://www.flyingmag.com/everything-you-need-to-know-about-... https://boltflight.com/loc-vs-ils-vs-gps-approach-understanding-modern-instrument-landing-techniques/ https://boltflight.com/loc-vs-ils-vs-gps-approach-understand... https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap1_section_1.html https://www.faa.gov/air_traffic/publications/atpubs/aim_html... https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System > "The Wide Area Augmentation System (WAAS) is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System (GPS), with the goal of improving its accuracy, integrity, and availability. Essentially, WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including approaches with vertical guidance to any airport within its coverage area. It may be further enhanced with the local-area augmentation system (LAAS) also known by the preferred ICAO term ground-based augmentation system (GBAS) in critical areas." > In 2007, WAAS vertical guidance was projected to be available nearly all the time (greater than 99%), and its coverage encompasses the full continental U.S., most of Alaska, northern Mexico, and southern Canada. At that time, the accuracy of WAAS would meet or exceed the requirements for Category 1 ILS approaches, namely, three-dimensional position information down to 200 feet (60 m) above touchdown zone elevation. Category II or III ILS GPS approaches are supported when the subject airport has a local reference station reporting corrections ("LAAS"). With enough precision, the aircraft can land itself with GPS and local corrections ("Autoland"). A King Air running Garmin's SafeReturn recently performed this autonomously with GPS alone (to the best of my knowledge). https://en.wikipedia.org/wiki/Local-area_augmentation_system https://en.wikipedia.org/wiki/Local-area_augmentation_system https://www.faa.gov/airports/planning_capacity/non_federal/gbas https://www.faa.gov/airports/planning_capacity/non_federal/g... Autoland saves King Air, everyone reported safe - https://news.ycombinator.com/item?id=46346214 https://news.ycombinator.com/item?id=46346214 - December 2025 (185 comments) Event ATC recording: https://www.youtube.com/watch?v=K3Nl3LOZNjc https://www.youtube.com/watch?v=K3Nl3LOZNjc Demo: https://www.youtube.com/watch?v=d-ruFmgTpqA https://www.youtube.com/watch?v=d-ruFmgTpqA
cmurf 3mo ago
In general I agree with this. (Without respect to this particular crash.) If GPS signal is sufficiently degraded or lost, TAWS is probably unavailable (highly dependent on what navigation system is on board). TAWS might have saved them. But needing TAWS implies loss of situational awareness. This flight crashed in the mountains ~6 miles north of the ILS 24 approach course. At ~12 miles out on the approach course, the ILS course width is ~1 mile. A full needle deflection translates to 1/2 mile off the course. A flight is not established on the approach course with a full needle deflection. Course intercept with localizer or VOR is basic instrument work - GPS not required. The flight requested ILS 24, later they indicated airport in sight, requested and received a clearance for a visual approach. That means pilots have full responsibility for terrain and obstruction clearance. The visual approach requirement is to maintain contact with with airport. It seems to me they went off course, by a lot, for reasons I'm not clear on, and then descended prematurely into hostile terrain at night, which is likely why they lost visual contact with the airport. The terrain blocked their view and by the time they realized they were descending into hostile terrain they crashed. If that's what happened, GPS signal loss is perhaps an instigating source of distraction and confusion but I do not see how it's a primary factor. If the signal becomes degraded, navigation should indicate it (auditory and visual) and that source is ignored entirely. Falling back to ground based navigation should be familiar, it doesn't need to be as precise as GPS, the instrument approach procedure has terrain clearance baked into it. Best practice is to follow the instrument approach procedure to the final approach fix, then do the visual approach - especially at night which many have argued constitutes instrument flight conditions - mountains will be invisible. Pitch black on black.
- cmurf 3mo ago
  Ok after rereading the preliminary report, ATC gave them a vector north and clearance to a named fix. They were not off course. While on a vector clearance, terrain and obstacle clearance is ATC's responsibility. Once the accident flight requested and received a visual approach clearance ~30 miles out, terrain and obstacle avoidance becomes pilot responsibility. It seems likely to me that whether GPS was working or not, whether RNAV 24 or ILS 24, they'd have requested a visual approach. And the pilots did not adequately account for the terrain between the flight and the airport when they initiated the descent, and descended below minimum safe IFR altitude. Further due to this flight operating under 14 CFR 135, there's a regulatory bridge to bind the flight to the (Part 135) Certificate Holder's operation specifications (OpSpecs). Pilots cannot operate outside of OpSpecs. It's possible the medivac company's OpSpecs require mandatory direct visual contact with terrain and obstacles - something that could not be achieved with 0% illumination due to no moon. Some OpSpecs will prohibit visual approaches at night to non-towered airports. SRR airport has no tower. I'm not familiar with this operator's OpSpecs.
smcg 3mo ago
Well in this case there were multiple failures... Should they have been identified earlier? Yes.
- coredog64 3mo ago
  It's a truism that every accident is actually a chain of events, or at least it was 30+ years ago at Embry-Riddle. Lower stakes situations recognize this with the "5 whys" technique.

toomuchtodo 3mo ago

Highly dependent on weather and the complexity of the approach. Clear skies and VFR? I would agree. Heavy weather and an instrument approach or confounding factors? Not accurate imho. > At midnight on May 14, eight minutes after Clark and Kawsara took off from Roswell, they told Albuquerque Center that they’d lost their GPS. Unable to navigate on their own, they asked that the controller give them a heading—a magnetic direction to fly in. The controller gave them a heading to fly west, and then, a minute later, to turn north. > The pilots said that they wanted to fly an RNAV approach to Ruidoso. This being ruled out while GPS is jammed, the King Air pilots changed their request and asked to use an alternate form of landing system called Instrument Landing System, or ILS, that doesn’t require GPS reception. At 12:05 am, the controller assured the King Air that they would provide them with vectors to guide them “in a couple of minutes.” In the meantime, they kept flying north. > In retrospect, tragedy might have been avoided if Albuquerque air traffic control had been able to pay closer attention to the young pilots in the King Air. But tonight they were busy. Three other aircraft also reported that they’d lost their GPS and needed help. One was struggling to get a bearing on a radio beacon. > As they turned and descended toward Ruidoso’s lights, what the pilots couldn’t see was the 10,000-foot-high mass of the Capitan Mountains lying across their path. As they drew closer, the dark mass of rock appeared to rise up, swiping away the lights of the valley. This could have created "confusion and a loss of situational awareness,” Browne says. “When those lights go out, man, you know you are in big trouble.” Potentially low time pilots with degraded navigation aids at night (midnight) got behind the plane in an area with terrain, along with a high workload ATC not able to provide assistance more rapidly. (disclaimer: have a private license)

27183 3mo ago
> Heavy weather and an instrument approach or confounding factors? Not accurate imho. Then what are you supposed to do when your GPS craps out on approach in low visibility and heavy weather? Obviously the answer is "fly the airplane". Which means you look at your artificial horizon, set trim and power for max climb, get to a safe altitude and figure it out. If you're paying attention you already have your chart folded to the airport you're landing at, so it shouldn't be too hard to orient yourself and figure out what's next. Either you'll be making another attempt at this airport without GPS or you'll be going somewhere else. There's never an excuse for failing to fly the airplane. That's basic airmanship. You need to be able to do it regardless of whether your GPS is working.
- toomuchtodo 3mo ago
  It's very easy to write this comment when you're not the one getting behind the plane in the middle of the night with multiple simultaneous challenges (speaking from experience; I can feel the anxiety writing this comment from similar "white knuckle" experience), and I agree, keep flying the plane. Systems fail, that is the point of investigating incidents to improve systems. Humans are always the weakest link. I agree that an experienced pilot should be able to safely land on an approach assuming a loss of GPS. (General aviation (GA) is significantly less safe than commercial air travel, tracking at roughly 1.0 to 1.1 fatal accidents per 100,000 flight hours. Statistically, GA's per-hour fatality rate is about 14 times higher than driving a car, carrying a risk profile comparable to riding a motorcycle) Edit: My hot take is more communication and training needs to go into "As the pilot, you should be prepared to lose GPS at any time at critical moments in the flight lifecycle." Are we letting folks fly in potentially adverse conditions leaning too heavily on GPS leading to potentially avoidable accidents? I don't know, the NTSB is likely better informed to say so or not. If I was a flight instructor, I'd probably include loss of GPS during instrument approach at night and/or in weather as an experience to cover.
  - 27183 3mo ago
    I've been in this situation too. But I was trained for it and had a mental checklist to follow. I never had a GPS, though. It seems from the details of the article, which you rightly highlighted, that the pilots were using their GPS as a crutch and had no ability to fall back on basic dead reckoning. It seems they didn't know where they were. That's pretty inexcusable, like embarrassing even. I don't fly anymore, but I see similar behaviors developing on the water. People who use chartplotters for navigation don't have a very good understanding of what's going on around them. If you're just interactively following a computed lay line or a plotted course you don't really need to know what the currents are doing. You don't need to know what the hazards are. You're not actively engaged in navigating the boat.
  - SoftTalker 3mo ago
    > General aviation (GA) is significantly less safe than commercial air travel Since I've been paying attention from the peanut gallery, watching Blancolirio videos, etc. I would never fly on a small private plane. Seems like once a week there is a crash of a small GA craft somewhere, often with fatalities, due to loss of control (i.e. nothing wrong with the aircraft). Pilots seem to become overconfident or complacent, make bad decisions instead of "gettimg out the credit card and booking a hotel" as Juan likes to say -- if you can afford to fly your own plane you can afford a night at a hotel. They can't handle loss of visual flight conditions. They don't recognize when they need to ignore their inner ear and trust the instruments. They can't recover from stalls or upsets (and actual practice isn't required, because that too caused a lot of crashes). Worse, they often take family and friends with them. There's a reason a lot of life insurance policies specifically carve out private aircraft operation or travel as an exception to coverage.
justinhj 3mo ago
They deferred navigation to ATC instead of using their own capabilities such as VOR.
- toomuchtodo 3mo ago
  They requested navigation assistance ATC could not promptly provide. I strongly agree the pilot in command could've done better, but if ATC was overloaded, they should've promptly communicated that to manage expectations that immediate help was not forthcoming. An aircraft covers a lot of ground "in a couple of minutes." (assuming ~120-200 knots) https://www.airresearch.com/Pilots/AIM-08/Chap6/aim0602.html https://www.airresearch.com/Pilots/AIM-08/Chap6/aim0602.html > a. Radar equipped ATC facilities can provide radar assistance and navigation service (vectors) to VFR aircraft in difficulty when the pilot can talk with the controller, and the aircraft is within radar coverage. Pilots should clearly understand that authorization to proceed in accordance with such radar navigational assistance does not constitute authorization for the pilot to violate CFRs. In effect, assistance is provided on the basis that navigational guidance information is advisory in nature, and the responsibility for flying the aircraft safely remains with the pilot. Potentially tangentially related to an overloaded and understaffed US ATC network, similar to the overloaded controller that led to the LaGuardia runway incursion on March 22, 2026. https://www.pilotsofamerica.com/community/threads/crj-collides-into-fire-engine-on-runway-at-la-guardia-3-22-26.153779/ https://www.pilotsofamerica.com/community/threads/crj-collid... ("What’s the bet that the controller had been overworked and the cab was understaffed? Seems to be an incredibly common thread lately.") American aviation is near collapse? - https://news.ycombinator.com/item?id=47494469 https://news.ycombinator.com/item?id=47494469 - March 2026 (106 comments) LaGuardia pilots raised safety alarms months before deadly runway crash - https://news.ycombinator.com/item?id=47503965 https://news.ycombinator.com/item?id=47503965 - March 2026 (310 comments) Two pilots dead after plane and ground vehicle collide at LaGuardia - https://news.ycombinator.com/item?id=47486386 https://news.ycombinator.com/item?id=47486386 - March 2026 (667 comments) https://news.ycombinator.com/item?id=47494936 https://news.ycombinator.com/item?id=47494936 (my comment with citations on this thesis) (my flavor of autism includes aggressive pattern matching)
  - wafflemaker 3mo ago
trollbridge 3mo ago
GPS is not, and never will be, reliable enough for IFR on its own. Relying on a tower in instrument conditions because GPS failed is unacceptable, because every other GPS user is in the same boat. If you’re flying IFR, you should have a working set of instruments and be using them. Why didn’t these pilots have their VORs tuned in for positioning?
- toomuchtodo 3mo ago
  > GPS is not, and never will be, reliable enough for IFR on its own. WAAS GPS (~7.6M accuracy) is reliable enough for IFR on its own that many approaches have removed legacy RF ILS equipment for instrument approaches (RNAV LPV with synthetic glidescope from GNSS). I would agree this does not apply to the vast majority of general aviation (although certified receivers supporting this are well within the reach of GA at ~$6k), but facts and specifics are important, so enumerating that GPS and these trimmings make it designed to replace traditional IFR equipment under certain circumstances. WAAS is not a paid service, the additional precision is free if your receiver and autopilot supports it. Further reading: https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/approaches https://www.faa.gov/about/office_org/headquarters_offices/at... https://www.aopa.org/news-and-media/all-news/2025/october/pilot/instrument-tip-gps-substitute-or-alternate https://www.aopa.org/news-and-media/all-news/2025/october/pi... ("Today most IFR pilots use GPS as a primary source of navigation, whether they’re flying a departure, airway, or arrival defined by VORs; or segments of approaches based on navaids or that require DME or ADF.") [My note: This is straight from the advocacy group for general aviation in the US, AOPA.] https://www.flyingmag.com/everything-you-need-to-know-about-rnav-gps-approaches/ https://www.flyingmag.com/everything-you-need-to-know-about-... https://boltflight.com/loc-vs-ils-vs-gps-approach-understanding-modern-instrument-landing-techniques/ https://boltflight.com/loc-vs-ils-vs-gps-approach-understand... https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap1_section_1.html https://www.faa.gov/air_traffic/publications/atpubs/aim_html... https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System > "The Wide Area Augmentation System (WAAS) is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System (GPS), with the goal of improving its accuracy, integrity, and availability. Essentially, WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including approaches with vertical guidance to any airport within its coverage area. It may be further enhanced with the local-area augmentation system (LAAS) also known by the preferred ICAO term ground-based augmentation system (GBAS) in critical areas." > In 2007, WAAS vertical guidance was projected to be available nearly all the time (greater than 99%), and its coverage encompasses the full continental U.S., most of Alaska, northern Mexico, and southern Canada. At that time, the accuracy of WAAS would meet or exceed the requirements for Category 1 ILS approaches, namely, three-dimensional position information down to 200 feet (60 m) above touchdown zone elevation. Category II or III ILS GPS approaches are supported when the subject airport has a local reference station reporting corrections ("LAAS"). With enough precision, the aircraft can land itself with GPS and local corrections ("Autoland"). A King Air running Garmin's SafeReturn recently performed this autonomously with GPS alone (to the best of my knowledge). https://en.wikipedia.org/wiki/Local-area_augmentation_system https://en.wikipedia.org/wiki/Local-area_augmentation_system https://www.faa.gov/airports/planning_capacity/non_federal/gbas https://www.faa.gov/airports/planning_capacity/non_federal/g... Autoland saves King Air, everyone reported safe - https://news.ycombinator.com/item?id=46346214 https://news.ycombinator.com/item?id=46346214 - December 2025 (185 comments) Event ATC recording: https://www.youtube.com/watch?v=K3Nl3LOZNjc https://www.youtube.com/watch?v=K3Nl3LOZNjc Demo: https://www.youtube.com/watch?v=d-ruFmgTpqA https://www.youtube.com/watch?v=d-ruFmgTpqA

cmurf 3mo ago

In general I agree with this. (Without respect to this particular crash.) If GPS signal is sufficiently degraded or lost, TAWS is probably unavailable (highly dependent on what navigation system is on board). TAWS might have saved them. But needing TAWS implies loss of situational awareness. This flight crashed in the mountains ~6 miles north of the ILS 24 approach course. At ~12 miles out on the approach course, the ILS course width is ~1 mile. A full needle deflection translates to 1/2 mile off the course. A flight is not established on the approach course with a full needle deflection. Course intercept with localizer or VOR is basic instrument work - GPS not required. The flight requested ILS 24, later they indicated airport in sight, requested and received a clearance for a visual approach. That means pilots have full responsibility for terrain and obstruction clearance. The visual approach requirement is to maintain contact with with airport. It seems to me they went off course, by a lot, for reasons I'm not clear on, and then descended prematurely into hostile terrain at night, which is likely why they lost visual contact with the airport. The terrain blocked their view and by the time they realized they were descending into hostile terrain they crashed. If that's what happened, GPS signal loss is perhaps an instigating source of distraction and confusion but I do not see how it's a primary factor. If the signal becomes degraded, navigation should indicate it (auditory and visual) and that source is ignored entirely. Falling back to ground based navigation should be familiar, it doesn't need to be as precise as GPS, the instrument approach procedure has terrain clearance baked into it. Best practice is to follow the instrument approach procedure to the final approach fix, then do the visual approach - especially at night which many have argued constitutes instrument flight conditions - mountains will be invisible. Pitch black on black.

cmurf 3mo ago
Ok after rereading the preliminary report, ATC gave them a vector north and clearance to a named fix. They were not off course. While on a vector clearance, terrain and obstacle clearance is ATC's responsibility. Once the accident flight requested and received a visual approach clearance ~30 miles out, terrain and obstacle avoidance becomes pilot responsibility. It seems likely to me that whether GPS was working or not, whether RNAV 24 or ILS 24, they'd have requested a visual approach. And the pilots did not adequately account for the terrain between the flight and the airport when they initiated the descent, and descended below minimum safe IFR altitude. Further due to this flight operating under 14 CFR 135, there's a regulatory bridge to bind the flight to the (Part 135) Certificate Holder's operation specifications (OpSpecs). Pilots cannot operate outside of OpSpecs. It's possible the medivac company's OpSpecs require mandatory direct visual contact with terrain and obstacles - something that could not be achieved with 0% illumination due to no moon. Some OpSpecs will prohibit visual approaches at night to non-towered airports. SRR airport has no tower. I'm not familiar with this operator's OpSpecs.

smcg 3mo ago

Well in this case there were multiple failures... Should they have been identified earlier? Yes.

coredog64 3mo ago
It's a truism that every accident is actually a chain of events, or at least it was 30+ years ago at Embry-Riddle. Lower stakes situations recognize this with the "5 whys" technique.