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I don't really understand why the plane was diverted because GPS was jammed; I get that it's important for navigation, but not how it's required for landing whe

I don't really understand why the plane was diverted because GPS was jammed; I get that it's important for navigation, but not how it's required for landing when they're that close. There's (iirc) close range guidance systems, and of course visual ones (lamps, stripes, etc).

mapt 2y ago
Commercial air travel is very risk-averse. Best practice is that if something unexpected occurs, and you have plenty of fuel to spare, you go and and find someplace else to land.
macguillicuddy 2y ago
My understanding is it depends on the amount of visibility, plus what type of approach they were on. One type of approach, an ILS, has big radio transmitters pointing from the runway into the air and allows the plane (either pilots or autopilot) to get close enough to the runway without visibility, and with enough precision, to land. In many circumstances ILS isn't available and an alternative is Required Navigation Performance (RNP) which uses GPS plus a ton of other inputs to give some amount of precision to the same end. If they're on an RNP approach but suffer a reduction in navigation accuracy then I imagine it's a policy 'go-around'. Even if there's enough visibility it allows the pilots to brief a 'visual' approach before attempting it.
Gathering6678 2y ago
Considering it's below 1000 feet, losing GPS could indicate an "unstablized" approach and require a go-around, as opposed to losing it at a higher altitude where the pilot could have more time to safely switch to alternatives (other navigating aids or go to visual?). Source: my guess after watching a lot of aviation YouTube videos......
- alistairSH 2y ago
  For anybody who doesn't know, a "stabilized approach" is an approach with a constant angle and speed as the plane descends and lands. This allows the plane to keep consistent control settings (flaps, throttle, etc). It's best practice/policy for all major airlines to use stabilized approaches and most/all require a go-around if the stabilized approach is interrupted (there are edge cases and exceptions).
rlpb 2y ago
Not all types of approaches are available at all runways (or airports), and sometimes they are down for maintenance. Specific runways may be required due to wind, aircraft weight and runway condition and length. Most airlines ban "circling approaches" (using an approach to one runway end and then circling visually to land at a other) for safety reasons. ILS, which is probably the "close range guidance" you are thinking of, must be installed, maintained and calibrated individually per runway end. Visual aids cannot be used for approach if there is low cloud. It is usual to be able to abort an approach and try again at the same airport using a different approach technology. But if the journalist wanted to find the most extreme example, it's not surprising that it happened at least once that an alternative wasn't available. This is probably "sampling bias"! Note that final operational decisions are made by the aircraft commander. Aircraft do not "get diverted", except by decision of the "captain".

mapt 2y ago

Commercial air travel is very risk-averse. Best practice is that if something unexpected occurs, and you have plenty of fuel to spare, you go and and find someplace else to land.

macguillicuddy 2y ago

My understanding is it depends on the amount of visibility, plus what type of approach they were on. One type of approach, an ILS, has big radio transmitters pointing from the runway into the air and allows the plane (either pilots or autopilot) to get close enough to the runway without visibility, and with enough precision, to land. In many circumstances ILS isn't available and an alternative is Required Navigation Performance (RNP) which uses GPS plus a ton of other inputs to give some amount of precision to the same end. If they're on an RNP approach but suffer a reduction in navigation accuracy then I imagine it's a policy 'go-around'. Even if there's enough visibility it allows the pilots to brief a 'visual' approach before attempting it.

Gathering6678 2y ago

Considering it's below 1000 feet, losing GPS could indicate an "unstablized" approach and require a go-around, as opposed to losing it at a higher altitude where the pilot could have more time to safely switch to alternatives (other navigating aids or go to visual?). Source: my guess after watching a lot of aviation YouTube videos......

alistairSH 2y ago
For anybody who doesn't know, a "stabilized approach" is an approach with a constant angle and speed as the plane descends and lands. This allows the plane to keep consistent control settings (flaps, throttle, etc). It's best practice/policy for all major airlines to use stabilized approaches and most/all require a go-around if the stabilized approach is interrupted (there are edge cases and exceptions).

rlpb 2y ago

Not all types of approaches are available at all runways (or airports), and sometimes they are down for maintenance. Specific runways may be required due to wind, aircraft weight and runway condition and length. Most airlines ban "circling approaches" (using an approach to one runway end and then circling visually to land at a other) for safety reasons. ILS, which is probably the "close range guidance" you are thinking of, must be installed, maintained and calibrated individually per runway end. Visual aids cannot be used for approach if there is low cloud. It is usual to be able to abort an approach and try again at the same airport using a different approach technology. But if the journalist wanted to find the most extreme example, it's not surprising that it happened at least once that an alternative wasn't available. This is probably "sampling bias"! Note that final operational decisions are made by the aircraft commander. Aircraft do not "get diverted", except by decision of the "captain".