DU Aviation Experts: I have a couple of questions.

[Pilotguy]

47. Some thoughts on the crash today...

The glideslope to runway 28L was out of service at SFO. The glideslope provides the vertical guidance for an ILS or Instrument Landing System. Even on clear days and when cleared for a visual approach it is SOP (standard operating procedure) at many airlines to fly the ILS if a runway is equipped with one.

I am reading some reports that the PAPI for 28L was also out of service at the time of the crash. I'm not sure how accurate those reports are. The PAPI or Precision Approach Path Indicator is an array of red and white lights on the side of the runway that provide visual vertical guidance to landing aircraft.

ATC is capable of and is required by FAA regulations to issue low altitude alerts to pilots when they dip below the glidslope. But they are required to do so only when an aircraft is cleared for an instrument approach. Flight 214 was cleared for a visual approach so no such warning would be required. I believe with the glideslope out of service ATC would not have been able to monitor the aircraft's descent anyway.

With the ILS and PAPI out of service the pilots of Flight 214 had no instrument or visual aids to establish the proper descent to the runway. This really shouldn't be a problem for experienced pilots. Pilots should be able to fly a visual approach without crashing the aircraft.

My speculation:

The pilots of Flight 214 were probably not faced with a similar situation with both ILS and PAPI or VASI out of service in quite a long time and they just misjudged the descent rate. A passenger interviewed on CNN said the pilot advanced the throttles just before impact. If the descent rate was too steep the pilot would get a "sink rate" warning but he may have been too low at that point to save the landing.

One other point: Korean pilots are trained very differently than American pilots. Korean pilots rely much more heavily on the automated features of modern aircraft like the autopilot and the auto-land feature of the B777. Faced with a true visual approach with no ILS or PAPI the pilots were forced to hand fly the approach, something, perhaps, they may not have done in quite some time.