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harshrealitytoday at 1:28 PM1 replyview on HN

Missing from the article is that, once the pilots reported to ATC that GPS was inoperable, ATC was going to have them circle to the right and guide them along the ILS approach, which would've avoided the worst of the mountains. ATC also asked the military to stop GPS jamming, which they did for a brief while... and the pilots probably noticed GPS start working again... except...

Instead, the pilots saw the airport visually and requested a visual approach. ATC cleared them, and told the military they could resume GPS jamming, meaning any terrain awareness warning system the pilots might have had or been relying on would no longer work. The visual approach involved a left turn and descending directly over the mountains.

blancolirio's video about this (second one, after the prelim investigation report): https://www.youtube.com/watch?v=Dcyup4xVQuM

He focuses on the fact that both instrument approaches were impossible under the conditions; gps jamming made RNAV impossible, and an inoperable weather broadcasting system at the destination made ILS impossible. The alternative, visual approach in mountainous terrain on a moonless night, is clearly unwise for inexperienced pilots.

One thing he doesn't mention, though, is that ATC could have waited until the plane was on the ground to tell the military they could resume GPS jamming, knowing this was a medevac flight lacking the usual planning and level of caution of typical pilots.


Replies

otekengineeringtoday at 3:01 PM

> ATC could have waited until the plane was on the ground to tell the military they could resume GPS jamming

He hinted at this when he mentioned that ATC was dealing with other flights complaining about loss of GPS and coordinating with white sands. ATC crew were probably just out of their depth and trying their best, same as the flight crew. I wonder what the experience level of the ATC crew was and how much pressure they were getting from white sands to keep the jamming up.