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I was on a plane that had engine issues during takeoff, front wheel off the ground. We slammed back down to earth and likewise they braked harder than I'd ever

I was on a plane that had engine issues during takeoff, front wheel off the ground. We slammed back down to earth and likewise they braked harder than I'd ever experienced. Lady's phone flew out of her hand. It was intense.

polishdude20 4y ago
Hmm that's interesting since by the time the front wheel comes off the ground, an airplane would normally be past V1 speed and they'd have to commit to the takeoff.
- CPLX 4y ago
  That’s generally true but the rule is that you never abort past V1 unless you have specific immediate reason to believe the aircraft cannot become and stay airborne. There aren’t a ton of reasons one might think that but a few come to mind like total engine failure or lack of elevator control or similar.
  - techdragon 4y ago
    I can only imagine that the pilot had reason to believe something was wrong the moment the forces began to lift the front wheel and change the aircraft dynamics, which definitely is in the extremely fast changing grey zone for a lot of conditions highly dependent on the exact aircraft and it’s current conditions. Light payload and fuel loading pushing V1 very close to takeoff speed and lower than the maximum numbers, headwinds, engine conditions, etc… it’s definitely a case of “sometimes pilots do have to make quick decisions” and my money is on engines or the hydraulics when they first took load on the moving surfaces as the aerodynamics shifted passing V1 towards takeoff speed.
  - stordoff 4y ago
    > lack of elevator control This was the case with Ameristar Charters 9363, which aborted after V1: > [T]he jammed elevator could only be detected once aerodynamic forces came into play — something which would only happen once the plane was already speeding down the runway. The NTSB was forced to come to an incredible conclusion: that there was no way for the pilots to have detected the problem until they attempted to rotate for takeoff. https://admiralcloudberg.medium.com/lesser-of-two-evils-the-crash-of-ameristar-charters-flight-9363-b31023d9a66a https://admiralcloudberg.medium.com/lesser-of-two-evils-the-...
  - polishdude20 4y ago
    In that case wouldn't the plane be at such a speed and distance along the runway as to not be able to physically stop before the end?
mgsouth 4y ago
Wow. That's almost unheard of. There's a speed called "V1"; this is the last possible moment for a pilot to start aborting the takeoff. There's another speed called "Vr", which is when the pilot starts the rotation (lifting the nose off the ground) [1]. Vr is higher than V1. Past V1 its unsafe to abort, even if a tire blows or an engine fails. The only time it would be aborted would be if the pilot thinks the plane is unflyable, such as both engines failing or controls not working. [1] https://www.aopa.org/news-and-media/all-news/2011/february/01/understanding-v1 https://www.aopa.org/news-and-media/all-news/2011/february/0...
- michaericalribo 4y ago
  Whoa fascinating. What makes it necessary to commit after V1?
  - remh 4y ago
    As per the linked website: " If the airplane reaches a peak speed of only 10 knots beyond V 1, the brakes must now dissipate 20 percent more energy than had the abort been initiated at V 1. Beyond the fact that there is no certification requirement for the brakes to be able to absorb any energy beyond that existing at the highest weight and V 1 combination demonstrated, there also is no performance data to know how much runway would be needed even if the brakes are able to handle the extra energy. Adding to the chaos, one brake must now absorb all the energy of the aircraft, as the blown tire’s brake has been rendered useless." Basically you'd be unlikely to get the airplane to stop before the end of the runway because brakes are not designed to handle breaking at such speed (keep in mind that an airplane lands at a slower speed than it takes off thanks to the flaps).
  - chrischattin 4y ago
    It’s typically because there is not enough runway remaining to stop the plane if you abort past V1.
  - t0mas88 4y ago
    The V1 decision speed is not fixed, it's calculated for each take-off based on weight, wind, runway conditions, maximum thrust settings etc. It meets these constraints: 1. Low enough such that if you try to stop from that speed you will stop before the end of the runway 2. High enough such that if you have an engine failure at that speed, you will make it airborne on the other engine before the end of the runway 3. Not higher than rotation speed (you can't decide to abort after pitching the nose up and getting the aircraft airborne) 4. Not lower then minimum control speed (you can't keep directional control in case of an engine failure below minimum control speed, so your only option is to abort) If there is no speed that meets all conditions, then your runway is too short and you can't go. Reducing weight helps, since you'll accelerate faster, stop easier, and take-off at a lower speed. So that's usually the solution if your runway isn't long enough. Constraint 1 is why you're committed to takeoff above V1. If you would try to stop above V1 there is no guarantee that you'll stop before the end of the runway. While you are guaranteed to be able to take-off above that speed, even after an engine failure. So you take the problem into the air, run checks, and return.

polishdude20 4y ago

Hmm that's interesting since by the time the front wheel comes off the ground, an airplane would normally be past V1 speed and they'd have to commit to the takeoff.

CPLX 4y ago
That’s generally true but the rule is that you never abort past V1 unless you have specific immediate reason to believe the aircraft cannot become and stay airborne. There aren’t a ton of reasons one might think that but a few come to mind like total engine failure or lack of elevator control or similar.
- techdragon 4y ago
  I can only imagine that the pilot had reason to believe something was wrong the moment the forces began to lift the front wheel and change the aircraft dynamics, which definitely is in the extremely fast changing grey zone for a lot of conditions highly dependent on the exact aircraft and it’s current conditions. Light payload and fuel loading pushing V1 very close to takeoff speed and lower than the maximum numbers, headwinds, engine conditions, etc… it’s definitely a case of “sometimes pilots do have to make quick decisions” and my money is on engines or the hydraulics when they first took load on the moving surfaces as the aerodynamics shifted passing V1 towards takeoff speed.
- stordoff 4y ago
  > lack of elevator control This was the case with Ameristar Charters 9363, which aborted after V1: > [T]he jammed elevator could only be detected once aerodynamic forces came into play — something which would only happen once the plane was already speeding down the runway. The NTSB was forced to come to an incredible conclusion: that there was no way for the pilots to have detected the problem until they attempted to rotate for takeoff. https://admiralcloudberg.medium.com/lesser-of-two-evils-the-crash-of-ameristar-charters-flight-9363-b31023d9a66a https://admiralcloudberg.medium.com/lesser-of-two-evils-the-...
- polishdude20 4y ago
  In that case wouldn't the plane be at such a speed and distance along the runway as to not be able to physically stop before the end?

mgsouth 4y ago

Wow. That's almost unheard of. There's a speed called "V1"; this is the last possible moment for a pilot to start aborting the takeoff. There's another speed called "Vr", which is when the pilot starts the rotation (lifting the nose off the ground) [1]. Vr is higher than V1. Past V1 its unsafe to abort, even if a tire blows or an engine fails. The only time it would be aborted would be if the pilot thinks the plane is unflyable, such as both engines failing or controls not working. [1] https://www.aopa.org/news-and-media/all-news/2011/february/01/understanding-v1 https://www.aopa.org/news-and-media/all-news/2011/february/0...

michaericalribo 4y ago
Whoa fascinating. What makes it necessary to commit after V1?
- remh 4y ago
  As per the linked website: " If the airplane reaches a peak speed of only 10 knots beyond V 1, the brakes must now dissipate 20 percent more energy than had the abort been initiated at V 1. Beyond the fact that there is no certification requirement for the brakes to be able to absorb any energy beyond that existing at the highest weight and V 1 combination demonstrated, there also is no performance data to know how much runway would be needed even if the brakes are able to handle the extra energy. Adding to the chaos, one brake must now absorb all the energy of the aircraft, as the blown tire’s brake has been rendered useless." Basically you'd be unlikely to get the airplane to stop before the end of the runway because brakes are not designed to handle breaking at such speed (keep in mind that an airplane lands at a slower speed than it takes off thanks to the flaps).
- chrischattin 4y ago
  It’s typically because there is not enough runway remaining to stop the plane if you abort past V1.
- t0mas88 4y ago
  The V1 decision speed is not fixed, it's calculated for each take-off based on weight, wind, runway conditions, maximum thrust settings etc. It meets these constraints: 1. Low enough such that if you try to stop from that speed you will stop before the end of the runway 2. High enough such that if you have an engine failure at that speed, you will make it airborne on the other engine before the end of the runway 3. Not higher than rotation speed (you can't decide to abort after pitching the nose up and getting the aircraft airborne) 4. Not lower then minimum control speed (you can't keep directional control in case of an engine failure below minimum control speed, so your only option is to abort) If there is no speed that meets all conditions, then your runway is too short and you can't go. Reducing weight helps, since you'll accelerate faster, stop easier, and take-off at a lower speed. So that's usually the solution if your runway isn't long enough. Constraint 1 is why you're committed to takeoff above V1. If you would try to stop above V1 there is no guarantee that you'll stop before the end of the runway. While you are guaranteed to be able to take-off above that speed, even after an engine failure. So you take the problem into the air, run checks, and return.