B737 QRH Loss of Thrust on Both Engines - interpretation question.
Joined: Jun 2000
Posts: 4,507
Likes: 4
From: last time I looked I was still here.
C.K.
Spot on. I wish there were more like us. Trapping, went out years ago, (should have). Training in TQ's is just that; introduce an experience to learn from, well briefed and pattered during. Training in recurrency; introduce an experience that has been discussed briefly, but not in depth, and 'have a go' and see what happens. Perhaps try again, if necessary, after a short de-brief. Oh that there was time. Let's put the value back into training and less ticking boxes, or crazy scenarios.
Rather than show a scenario that is so unlikely to happen I'd rather spend time educating the pilots properly about how the damn thing works, so that when the unlikely happens they can think for themselves and sort it out as best they can. Searching the SOP manual won't help, and saying prayers won't either. Cursing the day you spent €150,000 on a type rating won't do diddly squat. Having a fundamental understanding of the beast you are trying to control in an environment you have a vague appreciation of will give you a fighting chance.
Spot on. I wish there were more like us. Trapping, went out years ago, (should have). Training in TQ's is just that; introduce an experience to learn from, well briefed and pattered during. Training in recurrency; introduce an experience that has been discussed briefly, but not in depth, and 'have a go' and see what happens. Perhaps try again, if necessary, after a short de-brief. Oh that there was time. Let's put the value back into training and less ticking boxes, or crazy scenarios.
Rather than show a scenario that is so unlikely to happen I'd rather spend time educating the pilots properly about how the damn thing works, so that when the unlikely happens they can think for themselves and sort it out as best they can. Searching the SOP manual won't help, and saying prayers won't either. Cursing the day you spent €150,000 on a type rating won't do diddly squat. Having a fundamental understanding of the beast you are trying to control in an environment you have a vague appreciation of will give you a fighting chance.
Joined: Apr 2008
Posts: 525
Likes: 2
From: Nearer home than before!
CK, Rat5 I also agree. The scenario needs to be appreciated every time for the correct decision.
The Fundementals are if you are in the cruise, you'll need to get down for the Pressurization anyway, so get the speed up and see if one will start. Once you're lower, then the APU and bleed starting is an option. DO you dive for 10,000ft? Nah, I'd start trading speed for range soon after the APU starts up as There's 10-12 minutes of time in the 02 systems for the pax.
Having said that, I did try dead sticking in the SIM mid North Sea, and struggled to get down after circling AMS. Best glider I've flown for years....
The Fundementals are if you are in the cruise, you'll need to get down for the Pressurization anyway, so get the speed up and see if one will start. Once you're lower, then the APU and bleed starting is an option. DO you dive for 10,000ft? Nah, I'd start trading speed for range soon after the APU starts up as There's 10-12 minutes of time in the 02 systems for the pax.
Having said that, I did try dead sticking in the SIM mid North Sea, and struggled to get down after circling AMS. Best glider I've flown for years....
Joined: Jun 2000
Posts: 4,507
Likes: 4
From: last time I looked I was still here.
One shot immediately then, if no success, wait until FL250 IMHO. Save battery; it's all you've got. Concentrate on aiming at a suitable landing site within a comfortable radius. Note I didn't say airfield. Keep your options open. Having just seen a documentary about the Bonneville Flats I might choose that over any airfield. Biggest multi directional runway in the world. I'd hope not to need the fire trucks, but walk away from it.
Joined: Dec 2013
Posts: 1,396
Likes: 148
From: Weltschmerz-By-The-Sea Australia
It pays to have at least a nodding acquaintance with the airstart envelope. Pick a speed target at 25,000 and 10,000' so that you can interpolate mentally during the otherwise placid procedure. 
Energy bled off at a high speed cannot be recovered completely in a subsequent speed reduction to min drag. Min drag isn't always the best range number wither, depending on wind. But you guys know that, obviously.
When I flew 737's the TREs would take great pains to point out the start EGT limits applied for the second start. I would always get them to clarify that if the first engine took, say 900° to start up, then I couldn't have the second engine back if it exceeded 725° during its start? (This was always preceded by an ash encounter, by the way). There is often an urge to invent arbitrary limitations based on something unrelated mentioned in the FCOM, I have found.
To summarise...in a loss of both engines, you are keeping some engine restart attempts in reserve for what? There is no duty cycle for non starter assisted starts, and hence no limits published, reasonably imagined, nor, by any measure, logical. Die busy.
Energy bled off at a high speed cannot be recovered completely in a subsequent speed reduction to min drag. Min drag isn't always the best range number wither, depending on wind. But you guys know that, obviously.
When I flew 737's the TREs would take great pains to point out the start EGT limits applied for the second start. I would always get them to clarify that if the first engine took, say 900° to start up, then I couldn't have the second engine back if it exceeded 725° during its start? (This was always preceded by an ash encounter, by the way). There is often an urge to invent arbitrary limitations based on something unrelated mentioned in the FCOM, I have found.
To summarise...in a loss of both engines, you are keeping some engine restart attempts in reserve for what? There is no duty cycle for non starter assisted starts, and hence no limits published, reasonably imagined, nor, by any measure, logical. Die busy.
Joined: May 2007
Posts: 721
Likes: 1
From: Western Pacific
When I flew 737's the TREs would take great pains to point out the start EGT limits applied for the second start. I would always get them to clarify that if the first engine took, say 900° to start up, then I couldn't have the second engine back if it exceeded 725° during its start? (This was always preceded by an ash encounter, by the way). There is often an urge to invent arbitrary limitations based on something unrelated mentioned in the FCOM, I have found.
