Thanks, ATCBob.. I’m not, even on the internet, a .65 expert.

GF

 

Whats your take on this Skywest flight that descended below the minimum segment altitude?

https://www.youtube.com/watch?v=FMUJnFr99rY

 

Already been discussed

https://www.airlinepilotforums.com/safety/110739-good-day-gpws.html

 

https://www.avherald.com/h?article=4b3d8f81

 

Many, many years ago, when I was a new Captain on the 737, I was coming from SFO to LAX. Twas a dark and stormy night, and the OAT was about 4 Degrees C. We were being vectored for the ILS 24R, and told to descend to 2,500. Presumably that was MVA. Being retired, I no longer have access to current approach charts, but at the time there was a terrain feature at 1,488 feet about 15 miles on final for 24R. If I remember correctly this was actually a quarry with rapidly rising walls.

The F/O was the PF, and he was highly experienced, (ex-TWA instructor). We briefed the approach, including the 1,488 obstruction. We got a vector to about a 22 mile final at 2,500. We were cleared to intercept the localizer, and cleared for the approach. We did NOT believe that meant that we were cleared to climb to the higher altitude depicted on the approach plate for the R24R approach plate. We both knew that LAX approach routinely vectored aircraft across the 24 runways approach at 3,500.

Predictably, we got a GPWS at the quarry. I saw the rapidly rising radar altimeter going up thru 1,000, and I said simply "do it", and the F/O did as we trained. The GPWS stopped within 100 feet, so we stopped the climb before we got 200 feet off altitude. We reported the incident to ATC, but they did not seem particularly interested.

I did do an ASRS report to the FAA, and also a safety report to the company. The company did not seem interested, but the FAA did call me back. They seemed to be most interested in what repercussions may have occurred with the company. They seemed to lose interest when I said that their were no company repercussions, but that I was most concerned that their was a potential for a midair collision if somebody followed the GPWS maneuver too far, with the aircraft performing the escape maneuver climbing into a higher aircraft being vectored for a runway 25 approach.

Joe

 

We get in the habit of accepting ATC descents below published MORA, route, or even arrival altitudes because ATC has min vectoring altitudes which are not published for our reference.

Also ARRIVAL crossing restrictions are usually there for airspace management reasons, ex separate departures from arrivals. ATC can waive those if there's no traffic conflicts and they often do.

But APPROACH restrictions are often there for terrain clearance purposes, especially closer in. If you're actually established on the approach course, you should question any clearance to descend below published altitudes.

If given at or above, might as well just comply with published, especially in mountains on a non-precision approach


As always, maintain terrain awareness at all times.