Probable Cause Delta @ LGA MD80

Cherokee_Cruiser

Cherokee_Cruiser

Bronteroc
PROBABLE CAUSE
The National Transportation Safety Board determines that the probable cause of this accident was the captain’s inability to maintain directional control of the airplane due to his application of excessive reverse thrust, which degraded the effectiveness of the rudder in controlling the airplane’s heading. Contributing to the accident were the captain’s (1) situational stress resulting from his concern about stopping performance and (2) attentional limitations due to the high workload during the landing, which prevented him from immediately recognizing the use of excessive reverse thrust.



Landing sequence graphic:

Untitled2.png






Evacuation:

Untitled.png








PA / comms were down as a result of the accident sequence. As a result some FAs had to leave their assigned station to find out what's going on. To be fair, the NTSB did say there is no established procedure for what to do in a zero-comms situation for an evacuation. Reading the abstract though, still seems the NTSB criticized the crew decision not to hastily evacuate.


" 13. The flight and cabin crews did not conduct a timely or an effective evacuation because of the flight crew’s lack of assertiveness, prompt decision-making, and communication and the flight attendants’ failure to follow standard procedures once the captain commanded the evacuation. "




Abstract:

http://www.ntsb.gov/news/events/Documents/2016_laguardia_BMG_Abstract.pdf
 
At a really cheap-ass airline, the lack of any comm's from the flight crew in an accident, they'll self evacuate.
Aren't their bull horns for the FA's during times of no electrics, i.e. No PA?
 
Nark said:
At a really cheap-ass airline, the lack of any comm's from the flight crew in an accident, they'll self evacuate.
Aren't their bull horns for the FA's during times of no electrics, i.e. No PA?
Click to expand...

I'd think the initial confusion and crew members leaving their stations caused that delay in getting the evacuation order out.
 
Interesting. In a similar design with the same engines, we were always limited to 1.6 EPR for reverse, but I never knew why. Correlation!
 
Cptnchia said:
Above 1.6 EPR, the rudder gets blanked and you lose control effectiveness. On contaminated runways, we're now only limited to 1.3 EPR.
Click to expand...

MD88/90 fleet limit was always 1.3 on contaminated runways. Target on dry was 1.6 but after this incident a fleet bulletin came out that changed target EPR to 1.3 in dry and contaminated runways. Performance charts were also changed to reflect 1.3 instead of 1.6 on dry rwy.
 
??

Sounds like one person is saying it was 1.3 EPR after this accident, and another saying it was already that before.

The NTSB pulled MD88 data and according to the report, 100% of flights exceeded 1.3 on a contaminated runway and that there was no callout for EPR value during rollout.

What's surprising is the touchdown at the 500 ft marker and nose down by the 1000 ft marker. It's not like a long landing and felt the need to go near max reverse?


Glad no one was hurt and that it was a learning experience was MD operators.
 
That's actually a "newer" and not necessarily historical limitation on the aircraft. I dusted off the old manual under my office desk and there really wasn't a limitation at the time just 'guidance' and some tribal knowledge.

When I flew the mad dog, the only true guidance we had was use it "judiciously" on contaminated surfaces, the MD-90 w/FADEC you could do whatever, the -88 had a nasty split EPR issue so you crack them, then ease them about mid reverse with the warning that it may "blank" the tail in some circumstances and NEVER before the nosewheel touches the ground.

I do remember 1.6 being all you really wanted to use on a dry surface, but no limitation, at least that I can remember from my tenure about a hard limit on contaminated surfaces other than a basic warning.

I'm not sure I like the NTSB's findings because the mixed engine types do accelerate differently and sometimes have a exponential acceleration in reverse. I often remembered cracking the reversers slowly edging them higher and higher and at the blink of an eye, one is at 1.2 and the other is 1.7 or 1.8 and I'd curse then snap them back to stow them.

I'm not very happy with the NTSB's conclusion. But they don't hear me tho.
 
Correct me if I'm wrong, but isn't idle reverse the new recommended setting for normal landings?

They should add the thrust reversers on an MD80 to the list of the most useless things in aviation.
 
mastermags said:
Correct me if I'm wrong, but isn't idle reverse the new recommended setting for normal landings?

They should add the thrust reversers on an MD80 to the list of the most useless things in aviation.
Click to expand...
Idle reverse on a contaminated runway, up to 1.3 if needed. 1.3 on a dry runway, up to 1.6 if needed.

The only problem with the TRs sucking is that the brakes suck too.
 
Cherokee_Cruiser said:
??

Sounds like one person is saying it was 1.3 EPR after this accident, and another saying it was already that before.
Click to expand...

Let's just say that guys who've been here longer than 2 years basically still did it the way we've always done it, (see @Derg post,) and then there's the new and newer way.

Personally, regardless of runway condition, I just use idle reverse. Above that, all you're doing is converting fuel to noise.
 
At our shop, 1.3EPR in reverse has been a company limitation for any landing, for a long time. Also a PM callout on landing if either engine exceeds 1.3.

Loss of directional control/rudder blanking due to excessive reverse was listed as a contributing factor in the LIT accident in 1999.
 
You must log in or register to reply here.
Back
Top