Aircrash investigation S19 E10 Runway Breakup.
Overview:
Plane 737.
Pilot flying IMC into airport. (HEAVY rain)
Lands short - crashes.
Findings:
- The pilot used to fly turbo props and was used to doing landings "aiming for the green lights" rather than using the PAPI, or aiming for the "piano keys".
- The plane was descending at 1100 FPM. Boeing's specified max is 900.
- If the Rate of Descent is greater than 900 (fpm) it is an unstable approach.
- "He was coming in steep and ALWAYS below the glideslope."
My "problems":
In the review it is said:
In vertical speed mode the crew must manually select their rate of descent.
Um, duh! That's why it is called Vertical speed.
On the "He was coming in steep and always under the glideslope" part:
If the plane was ALWAYS under the glideslope, they wouldn't have reached Top Of Descent. Why were they going down?
Ok, maybe to try and sneak in under the weather.
Given the plane has a given Ground speed - and yes I get that this can vary with wind speed changes - the "Top of descent" is a function of altitude and ground speed if you want a constant rate of descent.
So, why wouldn't you use VS if you have a given altitude and ground speed?
It wasn't clear the airport had ILS. But did have PAPI lights.
ILS is better I know because if the wind speed changes - and therefore the ground speed - the plane's position on the glide slope will change and the plane will act accordingly.
On the Rate of Descent.
Doesn't that depend on the airspeed too?
If you are doing 600 kts IAS and a ROD of >900 FPM, yes you have a problem. But if you have an IAS of 160 kts and a ROD of >900 FMP, why is that a problem?
All the plane sees is "air over its wings" - be it going up, down, or level.
So I am not exactly sure I get why the crew using Vertical Speed mode is/was a problem.