Discussion
This afternoon I was on a flight into London City, during the latter stages of which the cap'n announced that we'd been making good time but now there was a bit of bother in that that the flaps weren't working, and we were diverting to Stansted; where we subsequently made a flaps-free 'n' fast, but otherwise happy, landing.
I know about the short runway and steep descent angle issues at London City, and why that would make you divert under the circumstances.
But my question is how or whether, after experiencing one system failure, the cap'n can be sure the undercarriage is going to deploy, the spoilers are going to raise, the brakes will work, etc? Does he just continue the rest of the flight as normal apart from the changes he makes in response to the failed system, or does he do any extra checks of the other stuff, or whatever? Why would it be OK to assume a fault was isolated to the reporting-as-failed subsystem, and that we were not just seeing the tip of an iceberg? [I ask because, with my personal luck, the discovery of a one subsystem failure within a any complex system would inevitably just be the start of things going from bad to worse.]
After we'd landed, the cap'n explained the presence of the airfield fire engines at the end of the runway, with all lights flashing, as standard procedure whenever a plane lands in a non-standard configuration. So what is the conceptual difference between a non-standard configuration landing and an emergency landing?
Immediately after we'd landed and turned off the runway, I saw two vehicles driving the length of the runway at great speed, a few seconds before the next jet landed. What was that about -- were they looking for bits that might have dropped off?
Lastly: in what lunatic marketing person's demented fantasy does the train from Stansted Airport to Liverpool St constitute an 'express'?
I know about the short runway and steep descent angle issues at London City, and why that would make you divert under the circumstances.
But my question is how or whether, after experiencing one system failure, the cap'n can be sure the undercarriage is going to deploy, the spoilers are going to raise, the brakes will work, etc? Does he just continue the rest of the flight as normal apart from the changes he makes in response to the failed system, or does he do any extra checks of the other stuff, or whatever? Why would it be OK to assume a fault was isolated to the reporting-as-failed subsystem, and that we were not just seeing the tip of an iceberg? [I ask because, with my personal luck, the discovery of a one subsystem failure within a any complex system would inevitably just be the start of things going from bad to worse.]
After we'd landed, the cap'n explained the presence of the airfield fire engines at the end of the runway, with all lights flashing, as standard procedure whenever a plane lands in a non-standard configuration. So what is the conceptual difference between a non-standard configuration landing and an emergency landing?
Immediately after we'd landed and turned off the runway, I saw two vehicles driving the length of the runway at great speed, a few seconds before the next jet landed. What was that about -- were they looking for bits that might have dropped off?
Lastly: in what lunatic marketing person's demented fantasy does the train from Stansted Airport to Liverpool St constitute an 'express'?
You couldn't land at City without flaps, with the steep glideslope you simply haven't got enough drag and the thing will just accelerate downhill.
The flaps and gear etc are all generally driven by the hydraulic systems (depending on the type of a/c) and you can see if the hydraulic system is OK usually by just looking at the pressure in the system. So I wouldn't be too worried about the gear not deploying just becausee the flaps aren't moving.
The flaps and gear etc are all generally driven by the hydraulic systems (depending on the type of a/c) and you can see if the hydraulic system is OK usually by just looking at the pressure in the system. So I wouldn't be too worried about the gear not deploying just becausee the flaps aren't moving.
Jimbo. said:
Boatbuoy said:
Isn't landing gear designed to be gravity deployable in the event of hydraulic failure?
AFAIK, yes 
Although there're circumstances wherein even that can't happen (seem to recall a Polish passenger a/c belly-landing not too long ago?).Expensive little breaker that will have been!
There can be knock on effects with the failure of one system - hydraulics for example provide service for many parts of an aircraft, so you can see how one failure could affect these systems. However, a huge amount of redundancy is provided to cover all the essentials. With the case of the flaps, it could have been an isolated cause like the surfaces becoming jammed - ie - the electrics or hydraulics powering the flaps may have been working fine, but the flaps themselves have failed. Most checklists will highlight other systems that are affected by a particular failure, so it removes the guesswork to a certain degree, but ultimately it lies with the crew to make the decision as to where to go.
In most cases, particularly a flap failure, is it prudent to head to an airport with a long runway. Having been into both City and Stansted, I'd have definitely done the same. Flap failures result in having to approach at a higher speed and as a result, increases the landing distance required. Your crew did entirely the right thing but not being pressured to make an approach into an airport with a steep glideslope, short runway and water at either end!!
In most cases, particularly a flap failure, is it prudent to head to an airport with a long runway. Having been into both City and Stansted, I'd have definitely done the same. Flap failures result in having to approach at a higher speed and as a result, increases the landing distance required. Your crew did entirely the right thing but not being pressured to make an approach into an airport with a steep glideslope, short runway and water at either end!!
Edited by 5150 on Monday 1st July 10:58
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