I find it a bit shocking they'd be caught by surprise by a planned GPS outage. The exercise happened as intended, and all aircraft in the affected areas should have received warnings BEFORE they even took off. These are not drug smugglers - they filed a flight plan before leaving the ground.
The automated weather service was also out. This made it difficult or impossible to use the ILS because they can't set the local altimeter. This was a swiss cheese chain of events. It was a moonless dark night so the mountains weren't visible.
What is the normal fallback for local weather service failure? Divert to an airport with working service? Proceed, using the "nearest working" information?
How much does air pressure vary over a region, and how quickly does it change?
I think it would be "fly vfr" but the main issue there is the wind direction, not the altimeter setting. In daytime you can read the wind sock while airborne but not possible at night.
Would they take off if they knew GPS would be jammed midway through the flight?
Had they known they wouldn't be able to rely on GPS, all that back and forth with ATC would not be needed, and they'd already have a plan B and a plan C for navigating.
It's unfortunately all slices of swiss cheese aligned perfectly, but I'd still blame the military for poking extra holes on the GPS slice.
> Would they take off if
medevac flight - there was probably some urgency.
Maybe. Urgency should not trump safety. A delay in transport is not worse than a dead patient, dead medics and flight crew, and loss of an aircraft.
And I am happy to be corrected but as I understand it, in the rural west more medical transport than you might think is by air. Distances are large, and population is sparse. You can cover more area with the same number of medics using a few airplanes instead of ground ambulances. So not all air ambulance service is critically urgent, unlike what we are used to in more populated areas.
The losses were higher than if they hadn’t flown that night. But, then, they didn’t know GPS would be down when they were midway through the flight.
They certainly should have known. The information about GPS jamming appeared as a NOTAM in their Foreflight (electronic flight bag application) briefing, which 14 CFR § 91.103 requires them to review before the flight.
We can't be sure whether or not they read the briefing, but the NTSB preliminary makes clear that they at least downloaded it to their EFB app.