Reading through some of the available 737 pr0n around the net I found a comment in one document that talks about situations in which the aircraft must land at the nearest suitable airport. One of these situations is where there is only one main AC power source remaining, e.g. one engine or the APU.In other words, if both engines are toasted and you're running on just the APU you may not use your discretion and continue the flight Captain, you must land at the nearest suitable airport. What on earth did Boeing think might happen that they felt it necessary to spell that one out ?? :( :(

Reading through some of the available 737 pr0n around the net I found a comment in one document that talks about situations in which the aircraft must land at the nearest suitable airport. One of these situations is where there is only one main AC power source remaining, e.g. one engine or the APU.In other words, if both engines are toasted and you're running on just the APU you may not use your discretion and continue the flight Captain, you must land at the nearest suitable airport. What on earth did Boeing think might happen that they felt it necessary to spell that one out ?? :( :(

Its probably legal stuff. Should the pilot continue forward to an airport around where best glide speed would put it, and then crash, Boeing can say they are not responsible. He should have opted for the nearer airport.

You'd think people would have to spell things out less frequently, but in the land of the United States we even have to point out that coffee is hot, so are you really surprised?

That checklist really doesn't apply to loss of both engines if that is what you are talking about. There is a different checklist for that.

Q. You have one engine out, and one working fine, do you continue or divert to nearest? A. How is your APU?

@Paul - logical, but only if only one engine stops. I was wondering why Boeing felt it necessary to specify that you must land asap after both engines have shut down.@Tom - not a checklist, just some text in a tech document that I won't specify or link to ;-)@Kyle - nope, not even slightly :( :(

The procedure is referring to the electrical generator which is being driven by the engine or APU, not the engine or APU itself. If only one AC generator is available you must land at the nearest suitable airport.Conn McCarthy

If you lose AC power most likely you lose a lot of your primary flight instruments (in the NG I imagine this leaves you without the displays), and you must solely rely on backups. With the battery being your only source of DC power you have maybe 20-30 minutes to put it on the ground. So of course you need to put the plane down ASAP. Not to mention depending on why the generator failed (anything from the spline shearing, to a short, or any other number of things) you could be possibly dealing with a potential fire situation. So either way it is a bad situation to be in all the way around. Sitting on the flight deck and not being able to go physically verify anything I would not want to be the Captain to continue flight thinking it is something minor and be wrong. You only get one shot to bring everyone down alive sometimes, and better to be safe than sorry.

EDIT: NVMD

This exact situation happened to a 747 a couple years ago. (yes, a four-engined 747). http://www.dailymail.co.uk/news/article-507018/British-holidaymakers-mid-air-terror-jumbo-jet-loses-power.htmlThis incident is proof that loss of electrical power does not necessarily = loss of engine power. Water from a galley leaked into the avionics area and shorted out the generator relays in this case. You can also lose generators themselves without losing the engines - the generator is a separate device attached the engine and can break down. While the chance of both gens breaking down on the NG is rare, it *could* possibly happen and so the QRH has to account for that situation. Aviation history is filled with "impossible" failure events that actually happened - read about United 232 in Sioux City, IA for an example.

This exact situation happened to a 747 a couple years ago. (yes, a four-engined 747). http://www.dailymail.co.uk/news/article-507018/British-holidaymakers-mid-air-terror-jumbo-jet-loses-power.htmlThis incident is proof that loss of electrical power does not necessarily = loss of engine power. Water from a galley leaked into the avionics area and shorted out the generator relays in this case. You can also lose generators themselves without losing the engines - the generator is a separate device attached the engine and can break down. While the chance of both gens breaking down on the NG is rare, it *could* possibly happen and so the QRH has to account for that situation. Aviation history is filled with "impossible" failure events that actually happened - read about United 232 in Sioux City, IA for an example.

I remember that Qantas incident well. The moral to the story is that there are some things that you just cannot ever anticipate but thankfully through excellent training, a good aircraft with good backup systems and a bit of luck, nobody died.

One AC source = Get back on the ground ASAP. However, One AC source can power both Main AC Transfer Buses via the Bus Tie Breaker/Bus Transfer. The common problem associated with this is no Automatic Approaches because the Bus Tie Breaker will open on final approach to separate and protect the DC system and to provide Autopilot electrical source protection. This is good protection when BOTH Generators are working but will cause the AP to disconnect when only on ONE Generator. Most of the time if a generator drops off-line the APU is always available and the flight can continue. The APU can provide electrical power on the NG up to FL410 (Max ceiling) and you still have two AC power sources. In the even you lose an engine. Its always good practice for the non-flying pilot to fire up the APU and get it started as soon as they have a free moment. The QRH will call for this but then you will be sitting around for about 1 min while the thing gets fired up. (For me in the engine failure on T/O - I will always fire up the APU once the flaps are up/light out along with selecting Max Cont Thrust, Level Change (if we still need to climb) and suggesting to engage the Autopilot to relieve some workload and free up some mental capacity.) Something to keep in mind are the cardinal rules of the electrical system on the 737:- No paralleling of AC sources- One source can power a bus at a time - last connected source will disconnect the previous source- Min 2 sources of AC power in the air

Ryan, thanks for clearing that up, if the generator can fail while the engine is still running then it makes perfect sense.