737NG Complete loss of electrical power. [Archive]

FlyingStone

19th Mar 2021, 10:03

You should still be able to fly by looking out the window, and using standby altimeter and airspeed indicator. If you're lucky and happen to be in an aircraft fitted with ISFD, that has its own battery that should last 150 minutes, so you get the artificial horizon as well in that case. Magnetic compass obviously works, but it may be a bit off, since it's normally calibrated with all the electrical equipment switched on.

Flight controls should work normally as you have both EDPs operating (otherwise it's back to manual reversion), but you lose the ability to extend flaps. Emergency landing gear extension should work as well. No reversers on landing, but normal brakes and nosewheel steering should still work.

Not sure if you'd be able to shut down the engines as all valves are electrically actuated, but if you've made it that far, that's the least of your problems :)

Centaurus

19th Mar 2021, 10:52

Unintended slight thread drift. Having done several simulated approaches to a power on ditching at night in a real four engined maritime aircraft of another era, survival at impact depends heavily on pilot raw data instrument flying skills. Rate of descent no more than 200 feet per minute and optimum nose attitude, IAS as slow as is considered safe. Then because the QNH may be unknown you need to be stablised under those conditions for the last 500 feet at least. In those days we laid our own flare path time permitting using flame floats.

With todays sophisticated simulators a simulated approach to ditching is feasible. Yet in my experience in the airline industry I have yet to see pilots demonstrate their skills at this sequence. Having said that, and probably because I have taken part in several "simulated" ditchings at night in a real maritime reconnaissance military aircraft over real water (requirement to go-around 200 ft above the sea), I can attest it takes very careful instrument flying when 200 miles out to sea at night where it is real black.

To those who say ditching an airliner is so remote so no need to demonstrate skill, consider the possibility of an uncontrollable engine or airframe fire and the need to get down quickly before control is lost and you are over water. A ditch or die situation so to speak.

For thirty minutes twice a year in a simulator, would that not be good confidence builder and value for money? After all, it is the last 1000 ft of descent which need to be practiced in tems of aircraft handling on instruments. Forget checklists and long briefings. That can be discussed in the briefing room. It is all about skilful attitude flying and careful throttle handling over a period of three or four minutes prior to impact. if you have never had the opportunity to practice a ditching approach on instruments, survival chances are slim if it happens for real. From experience I can tell you it takes several practices in the simulator before competency is assured. There are no second chances if it happens for real

Now back to the original post with apologies for hijacking the author's subject of total electrical failure over water.

Bergerie1

19th Mar 2021, 10:59

Centaurus, A very good point. Not unlike a glassy water landing in a float plane, but infinitely more difficult at night in total darkness.

Gin Jockey

19th Mar 2021, 11:21

you lose the ability to extend flaps. Emergency landing gear extension should work as well. No reversers on landing, but normal brakes and nosewheel steering should still work.

Not sure if you'd be able to shut down the engines as all valves are electrically actuated, but if you've made it that far, that's the least of your problems :)

Flaps will still work, it’s purely a hydro mechanical link from flap lever to flap actuation (thank you 1960s design) but no indication, asymmetry / over speed protection (FSEU obviously has no power). Try it in your next sim if you don’t believe me.
Engine fuel spar valve has its own battery so can always shut engine down.

BraceBrace

19th Mar 2021, 13:51

If you were unlucky enough to lose all generators (say a freak lightning strike) and you’re over the sea with the nearest airport 1 hour away (single battery installed).........what are your options?.......what happens when the battery dies?

I'm not a fan of these purely hypothetical questions. Why make it easy and take the NG? Take a 737 classic, 30 minute battery. Same rules apply.

The battery will die, probably before you know it (don't count on 30 minutes)... Still confused by people saying you can "fly" when the battery dies. Just pray you have a moon to help you out with your manual trim.

If it happens, you are not flying, you are trying to survive in the best possible way and you either die, or you become a living hero.

411A NG

19th Mar 2021, 14:57

sycamore

19th Mar 2021, 15:39

Surely you would have a GPS in your bag,or on your wrist...????

FlyingStone

19th Mar 2021, 16:32

Flaps will still work, it’s purely a hydro mechanical link from flap lever to flap actuation (thank you 1960s design) but no indication, asymmetry / over speed protection (FSEU obviously has no power). Try it in your next sim if you don’t believe me.
Engine fuel spar valve has its own battery so can always shut engine down.

Ah, right. I thought everything goes through FSEU on the NG.

What's electrical concerning normal gear extension?
What about spoiers?
Reversers?

You're right about the gear and spoilers - they should operate normally, except for ground spoilers of course.

A lot of relays and electrically operated valves need to be powered in order to deploy thrust reversers. Think about air/ground logic, radio altimeter, etc.

WhatsaLizad?

19th Mar 2021, 17:09

I glad to finally see a subject that recognizes the problem flying the NG and the even the 737MAX ETOPS or remote areas.

tdracer

19th Mar 2021, 18:03

To those who say ditching an airliner is so remote so no need to demonstrate skill, consider the possibility of an uncontrollable engine or airframe fire and the need to get down quickly before control is lost and you are over water. A ditch or die situation so to speak.

For thirty minutes twice a year in a simulator, would that not be good confidence builder and value for money? After all, it is the last 1000 ft of descent which need to be practiced in tems of aircraft handling on instruments. Forget checklists and long briefings. That can be discussed in the briefing room. It is all about skilful attitude flying and careful throttle handling over a period of three or four minutes prior to impact. if you have never had the opportunity to practice a ditching approach on instruments, survival chances are slim if it happens for real. From experience I can tell you it takes several practices in the simulator before competency is assured. There are no second chances if it happens for real

We'd had this sort of discussion with the FAA more than once - not specifically about water ditching, but about 'why can't we train them for this in the simulator'.
Bottom line, simulator time is valuable. You need to prioritize what you're going to train for. And water ditchings of commercial airliners is extremely rare - two in the last 50 years, and those had extenuating circumstance. Sully didn't need to land on the water - he chose that as the best option rather than coming down in the middle of the city. Ethiopian was a hijacking.
Bottom line, there are more likely emergency scenarios that need to be trained for with the limited amount of sim time.

Banana Joe

19th Mar 2021, 18:16

You're forgetting about an ATR that had to ditch in the Mediterrenean Sea. Also the Air Transat A330 event caused by a fuel leak was a close call.

FlyingStone

19th Mar 2021, 18:20

I glad to finally see a subject that recognizes the problem flying the NG and the even the 737MAX ETOPS or remote areas.

You're talking about a triple failure to get there, after which the aircraft is still flying normally, albeit for a limited period of time, and is then still controllable with extremely limited instrumentation.

737 has been flying for more than 50 years and I haven't heard of any incidents where all three AC sources have failed. If you know of any, please share, it would be an interesting read.

WhatsaLizad?

19th Mar 2021, 18:48

BraceBrace

19th Mar 2021, 20:10

I glad to finally see a subject that recognizes the problem flying the NG and the even the 737MAX ETOPS or remote areas.

You can have a gen failure, but the problem shouldn't go "far" as AC sides are not interconnected (no parallelling of AC sides). And there is a mandatory backup (APU).

If you would end up with two generators at departure you would never end up beyond non-etops, and mentally you are ready for diversion as soon as one other gen would fail in a non-etops environment. Again, 2 not connected systems. And Boeing procedures in case of single generator are simple: land. So this cannot really happen "all of a sudden".

If we consider "user" failures, bus breakers would pop and the fault would be isolated without reaching a power source.

There's a lot that can happen, but there's no need to stretch your lottery chances of I don't know how many unrelated failures happening at the same time... History has shown humanity is more prone to "forgotten" kg to lbs conversions than electrical bugs taking down full electrical systems.

FlyingStone

19th Mar 2021, 20:28

The number of possible diversion runways available to become even more limited in the case of the MAX after losing all generators.

Any particular reason why MAX would be more limited in that regard than NG?

excrab

19th Mar 2021, 20:48

FS,
Curious as well regarding the number of jet transport aircraft that have ended up on battery power. I am also unsure of the MEL practices around the world. Agreed that a triple generator failure would be extremely rare in the 737 case, but dispatch with 1 engine generator inop might have an effect on the probabilities given the sometimes temperamental aspects of APU's. The number of possible diversion runways available to become even more limited in the case of the MAX after losing all generators.

The 737 is ranging far more than it has in the last 50 years.

I only have experience of one company’s ETOPS requirements on the NG so it’s not definitive, but we couldn’t dispatch an ETOPS flight unless both engine generators and the APU generator was serviceable. In flight the APU had to be started prior to the ETOPS entry point and if it didn’t start or one of the engine driven generators failed prior to the entry point then we had to re-route to ensure we remained within one hour of a suitable airfield. I would imagine that would apply to most ETOPS aircraft unless they have a RAT that can provide sufficient power if one of the other sources fails.

WhatsaLizad?

19th Mar 2021, 21:02

Any particular reason why MAX would be more limited in that regard than NG?

Required runway length for the MAX with a loss of all generators scenario. I'm not sure of the reason, but the loss of anti-skid along with the loss of the electric flight/ground spoilers might be the culprit. The numbers are surprisingly large, especially for a wet/good runway.

tdracer

19th Mar 2021, 22:41

I only have experience of one company’s ETOPS requirements on the NG so it’s not definitive, but we couldn’t dispatch an ETOPS flight unless both engine generators and the APU generator was serviceable. In flight the APU had to be started prior to the ETOPS entry point and if it didn’t start or one of the engine driven generators failed prior to the entry point then we had to re-route to ensure we remained within one hour of a suitable airfield. I would imagine that would apply to most ETOPS aircraft unless they have a RAT that can provide sufficient power if one of the other sources fails.

ETOPS MEL's are more restrictive - I don't think any MEL for ETOPS allows dispatch with only two generators - regardless of aircraft type.

Banana Joe, I should have specified 'commercial jetliner'. The point remains - jetliners having to ditch is very, very rare. Compare that to spacial disorientation leading to a loss of control - multiple crashes in just the last decade. Sim time can be better spent.

kiwi grey

20th Mar 2021, 00:21

Banana Joe, I should have specified 'commercial jetliner'. The point remains - jetliners having to ditch is very, very rare. Compare that to spacial disorientation leading to a loss of control - multiple crashes in just the last decade. Sim time can be better spent.

Apart from Capt Sullenberger's remarkable display of skill, how many jet aircraft with underslung engines have been successfully ditched? I think the answer is "none", and that the number of attempts can be easily counted on the fingers.
Yes, IMHO sim time can be much better spent.

Dave Therhino

20th Mar 2021, 03:05

Engine fuel spar valve has its own battery so can always shut engine down.

I’m pretty sure that’s not correct. You reading that in a Boeing manual of some kind?

Dave Therhino

20th Mar 2021, 03:12

You're talking about a triple failure to get there, after which the aircraft is still flying normally, albeit for a limited period of time, and is then still controllable with extremely limited instrumentation.

737 has been flying for more than 50 years and I haven't heard of any incidents where all three AC sources have failed. If you know of any, please share, it would be an interesting read.

There have been several events of loss of all normal AC power on the 737NG. Also at least two on the 767 I can recall.

Generator failures are almost never completely independent. Failure of the first one usually causes an increase in load on the remaining generator(s), often to their load limit, which can cause another generator or switching equipment to fail. Also, on an NG the third source is the APU generator. APU inflight start reliability is at best in the 99% range.

Also, adding to the list of what doesn’t work when all normal ac power is lost, add the fuel pumps. You are on suction feed if AC power is lost. If you are at high altitude with warm or unweathered fuel when this happens, you may experience a flame out on both engjnes.

Gin Jockey

20th Mar 2021, 06:20

I’m pretty sure that’s not correct. You reading that in a Boeing manual of some kind?

the FCOM makes no mention of it.

Both iPad apps for 737 I have mention it (737 cockpit companion and 737 MRG)

“spar valve mounted on the front spar outboard of each strut
- access is through an access panel on the leading edge
- has backup nicad battery to make sure it always has power to close
- the fuel spar valve actuator is interchangeable with the crossfeed valve actuator”

“a dedicated fuel spar valve battery ensures electrical power to close the valves should the hot battery bus become unpowered”

I’ll ask an engineer when I am at work tomorrow.

George Glass

20th Mar 2021, 07:54

There have been several events of loss of all normal AC power on the 737NG. Also at least two on the 767 I can recall.

Generator failures are almost never completely independent. Failure of the first one usually causes an increase in load on the remaining generator(s), often to their load limit, which can cause another generator or switching equipment to fail. Also, on an NG the third source is the APU generator. APU inflight start reliability is at best in the 99% range.

Also, adding to the list of what doesn’t work when all normal ac power is lost, add the fuel pumps. You are on suction feed if AC power is lost. If you are at high altitude with warm or unweathered fuel when this happens, you may experience a flame out on both engjnes.

BS

Name one.

I have flown many thousands of hours on the NG and never heard of one.
The NG has one of the simplest and most robust electrical systems there is.
I’ve been hit several times by lightning and it was not an issue.
Just lots of paperwork.

BraceBrace

20th Mar 2021, 10:23

I only know one case on a B727 where a water leak whiped out the complete electrical system, and that was pretty much in the departure sequence so the aircraft was back on the ground in little time.

In the simulator I have seen many bus failures, for some reason my company loved these during recurrents as for the "pilot side", there are a lot of little unrelated issues to deal with, some more apparent than others. But the result is always a no rush situation...

As for reality: single drive failures, gen failures, I remember somebody had a battery bus failure in the UK with some smoke?

So a full and non-recoverable loss of all AC power generation is really lottery level stuff.

RAWLAW

20th Mar 2021, 11:23

UAL 854 on April 13, 2004. My younger brother Brian Witcher was Captain. ALPA Superior Airman awarded to the crew. Root cause was corrosion at the AC/DC grounding bracket which caused a nearly continuous loss of electrical power. This was an ETOPS aircraft (B767-300) and if not for the emergency landing at BOG after 42 minutes it would have been a disaster. There is a good read on this in the October 2005 ALPA magazine. What I never quite understood was the inability to select the HMG or RAT on the 767 although due to the nature of the failure (total loss of the grounding of current) I believe it would not have made any difference. I myself flew for EAL from 1979 to the strike in 1989 on the 727, A-300 and the DC-9. Not pertinent to this topic but I just retired this month from a single corporate job I held from 1990. Flew the CL60, GV and G550.

WhatsaLizad?

20th Mar 2021, 14:32

So a full and non-recoverable loss of all AC power generation is really lottery level stuff.

Maybe, maybe not. As I mentioned, I don't know the exact numbers, but there is another consideration, the numbers across the civil aviation fleet might not be well known since a loss of Engine and APU generators has been a non-event in most aircraft types. Lottery level failures would probably apply to the 4 and 3 engine types where one has 4-5 Generators and maybe RAT backup. On the 2 engine types, the older 767/757 ER aircraft were equipped with hydraulic generator backup, providing 4 sources of flight display redundancy. On 2 engine Airbus, my understanding is the the RAT will provide the same.

The 737NG/MAX have reduced the number of electrical backups to 3. What I don't pretend to know is the MTB failure design specs on the NG/MAX. Have they improved significantly over the years? Hopefully yes. One still has to admit that no matter how good the odds, the aircraft is unflyable IFR after the IFSD battery dies after a loss of all generators. On other civil types with electric RAT options, not so much. The MAX also requires significant runway length in that scenario.

The Lottery jackpots for 3 numbers are significantly less than those for 4 or 5 numbers ;)

FlyingStone

20th Mar 2021, 18:04

One still has to admit that no matter how good the odds, the aircraft is unflyable IFR after the IFSD battery dies after a loss of all generators. On other civil types with electric RAT options, not so much.

If I'm not mistaken, the ISFD is normally powered by the DC standby bus, which will be powered by battery in the event of loss of all AC power. I'd guess that most 737NG aircraft (and certainly those that are ETOPS certified) are equipped with two batteries. So we are talking 60 minutes on batteries + another 150 minutes on the ISFD battery, total of 210 minutes. 737 NG/MAX are certified to ETOPS-180, so even if the loss of AC power would be at the critical point, it would still give crew a 30 minute margin, assuming battery capacity is what it should be. Note that very few (my guesstimate would be sub 1%) 737 flights worldwide include an ETOPS segment to begin with.

It's a pretty much very hypothetical scenario at best. Remember, at the end of the day, even the most modern aircraft only have dual-redundancy when it comes to pilots on board. And dual pilot incapacitation due to oil fumes is probably much more likely than a full electrical failure exactly when the aircraft happens to be far over the ocean.

WhatsaLizad?

20th Mar 2021, 18:37

FS,
Not sure of battery power on STBY. I've never seen the 60 minute number for two. As for the IFSD, the extra time is nice, but without any Nav or Comm source, the 737 is less redundant than other aircraft. There seems to be a common theme that it's never happened so it's not a problem. If so, perhaps the other fleet types can deactivate the backup generator option of their RAT's to save maintenance costs.

WhatsaLizad?

20th Mar 2021, 18:48

70 Mustang,

Great info, thanks!

Our manuals including the QRH have been dumbed down so much that information is excluded. While flying in the Domestic US? So what? Plenty of options within 30 minutes. In other areas such as over the Amazon, 60 minutes of Nav and Com along with the IFSD backup time after that should cover the areas of concern in my earlier posts.

70 Mustang

20th Mar 2021, 18:53

https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/2000x1156/8c55f773_2b59_4c89_81f8_08e5efb1fb51_6a80d1aeda9c6cb752c3534 2f7bd200755cdda0c.jpeg

FlyingStone

20th Mar 2021, 20:20

If so, perhaps the other fleet types can deactivate the backup generator option of their RAT's to save maintenance costs.

I'm not sure how well FBW works without any electrics.

NWA SLF

20th Mar 2021, 21:57

Everybody talks about Sully but didn't Captain Rozaq ditch his 737 Classic with both engines out due to intense rain - 1 fatality out of 60 on board. And although the gear was down, Air Niugini also made a water landing, 1 fatality out of 47 on board. If I recall on the Garuda incident, the battery was in poor condition so all electrical power was lost prior to ditching.

Dave Therhino

20th Mar 2021, 22:12

the FCOM makes no mention of it.

Both iPad apps for 737 I have mention it (737 cockpit companion and 737 MRG)

“spar valve mounted on the front spar outboard of each strut
- access is through an access panel on the leading edge
- has backup nicad battery to make sure it always has power to close
- the fuel spar valve actuator is interchangeable with the crossfeed valve actuator”

“a dedicated fuel spar valve battery ensures electrical power to close the valves should the hot battery bus become unpowered”

I’ll ask an engineer when I am at work tomorrow.

What you quoted seems quite clear. If it's in a system description or training material that came directly or indirectly from Boeing, then I think you can assume it's accurate. I just don't remember seeing reference to a dedicated battery for the spar valve in the engineering documents covering the fuel system description, the rotorburst safety analysis, or powerplant fire safety. Learned something new today. Thanks.

Dave Therhino

20th Mar 2021, 22:15

I'm not sure how well FBW works without any electrics.

I'm only familiar with the 777 FBW, which has dedicated generators on the engine gearbox for the FBW system. That system will function if all normal AC power is lost, and even if standby DC is lost. I imagine the 787 and the Airbus systems are the same, but don't know that for a fact.

George Glass

20th Mar 2021, 23:12

The NG only has a useful endurance of around 6 hours.
The ETOPS sector of 99% of flights is usually short.
There is no need for more redundancy.
Running the APU during the ETOPS sector is enough.
Same reason it only has 2 IRSs.
In fact my operator requires me to turn the APU off exiting the ETOPS sector to save fuel.

BraceBrace

20th Mar 2021, 23:24

The Lottery jackpots for 3 numbers are significantly less than those for 4 or 5 numbers ;)

Don't understand me wrong, I understand what you are trying to say. But you are talking about non-recoverable failures. The B767 had a common cause which is (probably) a result of non-bullet-proof failure analyses (well failure analyses will never be bullet proof). But such discoveries will certainly lead to modifications to aircraft or maintenance changes and hence shouldn't happen anymore.

The Boeing checklists in these cases aim at recovery of systems: they isolate and try to re-establish step by step. Ie, it's a known basic sim-scenario on the B737 to trigger a complete loss through an AC demand system (hydraulic pump), and have the crew walk through the checklists and identify the cause. The reasoning is 3 or even 2 different generators (power generation) on themselves don't fail around exactly the same time, those do require lottery number chances. A user can trigger the failure, but in these cases generators should be recoverable.

I do have to say I started on non-EFIS classic 737's. The "one fails, one overloads" could indeed be a problem because the APU generator did not have the same output as an engine driven generator, and the APU itself was dodgy to start... You also had 30' of battery life (if the battery was new) and if you wanted to start a dodgy APU you lost a couple of minutes already... Meanwhile, the flying pilot was looking at tiny standby dials. At a certain point he would discover the trim is not working, you are on manual trim now. And when you've finally "composed yourself", the dreadfull "tuut tuut tuut" comes on and you have to reach for the oxygen mask. How much time left now? About 20 minutes to land? Then came the EFIS (hey look the captain has good instruments to fly these 20 minutes!).

This sounds like story telling, but I only mention it to point out that - even on battery only - it's not that easy. The captain is flying and pretty much has to do... everything.

Then came the NG... 60 minutes battery? Holy moly... So it is 60 minutes to reach an airport but more importantly... 60 minutes to try to recover something. Because chances are big that one of those 3 generators will be recoverable. Non-recoverable power generation - IS a case of lottery numbers...

But I'll take the NG any day, beats the 30 minute battery classic ;-). Same rules did apply though.

BraceBrace

20th Mar 2021, 23:32

I'm only familiar with the 777 FBW, which has dedicated generators on the engine gearbox for the FBW system. That system will function if all normal AC power is lost, and even if standby DC is lost. I imagine the 787 and the Airbus systems are the same, but don't know that for a fact.

My former bosses tried extensively to have a complete electrical failure in the 777 simulator to create some kind of a scenario. I believe they got "pretty far", but the word I heard was "ridiculous" and I've never seen it in a recurrent afterwards...

Commander Taco

21st Mar 2021, 03:27

I did the B777 course in Seattle in 2008 and I recall our Boeing simulator instructor (who was fully qualified on type) telling us that when the 777 electrical fault analysis was done, it was realized that the 777 system redundancy and architecture made it statistically more probable that a 747 could experience a complete electrical loss of power than a 777.

oceancrosser

21st Mar 2021, 10:47

I only have experience of one company’s ETOPS requirements on the NG so it’s not definitive, but we couldn’t dispatch an ETOPS flight unless both engine generators and the APU generator was serviceable. In flight the APU had to be started prior to the ETOPS entry point and if it didn’t start or one of the engine driven generators failed prior to the entry point then we had to re-route to ensure we remained within one hour of a suitable airfield. I would imagine that would apply to most ETOPS aircraft unless they have a RAT that can provide sufficient power if one of the other sources fails.

One genarator is MEL-able for ETOPS (120min) in EASA land at least. I remember a different kind of incident though on a classic, where the battery would not charge. The flight was going oceanic and at around TOC they turned back ( all generators good), but yet the main battery was pretty drained when they landed from a visual approach. They were losing a lot of instruments, radios, VHFNAV etc. Don´t remember what was considered cause.

Centaurus

21st Mar 2021, 12:13

I remember a different kind of incident though on a classic, where the battery would not charge.

The classic of all time (no pun intended) was the Garuda 737-300 that ditched in a river in Indonesia in January 2002 in an all flaps up configuration after flying into a 75,000 ft super-cell CB.
:As the Boeing 737-300 (https://en.wikipedia.org/wiki/Boeing_737_Classic) aircraft was on approach to its destination, the pilots were confronted with substantial thunderstorm activity visible ahead and on their onboard weather radar.[2] (https://en.wikipedia.org/wiki/Garuda_Indonesia_Flight_421#cite_note-Final_NTSC-2) They attempted to fly between two intense weather cells visible on their radar. They later entered a thunderstorm containing heavy rain and hail. About 90 seconds later, as the aircraft was descending through 19,000 ft (5,800 m), both CFM International CFM56 (https://en.wikipedia.org/wiki/CFM_International_CFM56) engines experienced a flameout (https://en.wikipedia.org/wiki/Flameout), which resulted in the loss of all generated electrical power.

Both engines were set at their flight-idle power setting before flameout occurred. The crew tried unsuccessfully to restart the engines two or three times. They then tried but failed to start the auxiliary power unit (https://en.wikipedia.org/wiki/Auxiliary_power_unit) (APU), at which time total electrical power loss occurred. (During the later investigation, the NiCd (https://en.wikipedia.org/wiki/NiCd) battery was found to have been in poor condition due to inadequate maintenance procedures.) . As the aircraft descended through the lower layer of clouds at approximately 8,000 ft (2,400 m), the pilots saw the Bengawan Solo River (https://en.wikipedia.org/wiki/Bengawan_Solo_River) and decided to attempt to ditch in the river with the flaps and gear retracted. The ditch procedure was successful, leaving the aircraft settled down on its belly in the shallow water, with the fuselage, wings and control surfaces largely intact. There was no fire.

The investigation revealed a poorly maintained radome that resulted in a very much reduced range. When the crew tried to start the APU following the double engine flameout due rain ingestion, the battery failed simultaneously which left the crew with loss of all electrics in IMC.
The standby artificial horizon failed due loss of electrical power but what saved the day was the aircraft broke clear of cloud just as the standby AH gave up the ghost and toppled. The ditching at 180 knots was well handled and everyone escaped apart from one unfortunate cabin attendant trapped down the back when the floor collapsed.

Sounds like a good simulator exercise designed to sort the men from the boys! Even the most brutal of simulator instructors would never dream up such an unlikely combination of failures in IMC and heavy turbulence. Yet it happened for real that day.

See full report: https://en.wikipedia.org/wiki/Garuda_Indonesia_Flight_421#:~:text=A%20Garuda%20Indonesia%2 0Boeing%20737,similar%20to%20the%20accident%20aircraft.&text=On%20January%2016%2C%202002%2C%20the,one%20fatality%20a nd%20several%20injuries.

highflyer40

24th Mar 2021, 20:58

Surely you would have a GPS in your bag,or on your wrist...????

My GPS has worked on my phone on every flight I have been on. That will get you pretty close.

WhatsaLizad?

25th Mar 2021, 14:01

I'd utilize every asset of course, but we don't operate aircraft hoping someone has something in their bag to help out.

highflyer40

25th Mar 2021, 14:38

We also don’t operate aircraft that have lost all electrical power maybe 2 hours from land over the sea in bad weather. At least we hope not! If it does happen it’s nice to know where you are.

WhatsaLizad?

25th Mar 2021, 17:21

I beg to differ. The MAX may be over the middle of the Amazon forest without an airport with suitable runway length available under 60 minutes of flight time remaining for navigation.

BraceBrace

26th Mar 2021, 08:03

ETOPS or not?

FlyingStone

26th Mar 2021, 09:50

Required runway length for the MAX with a loss of all generators scenario. I'm not sure of the reason, but the loss of anti-skid along with the loss of the electric flight/ground spoilers might be the culprit. The numbers are surprisingly large, especially for a wet/good runway.

Have you got any specific figures by chance? It'd be interesting to see how long runways are we talking about.

WhatsaLizad?

26th Mar 2021, 17:17

ETOPS or not?

Non-ETOPS.

Wondering if ETOP's 737's have 2 batteries as well. Not sure my company ordered that option from the Dealer. Manuals don't reference 2.

WhatsaLizad?

26th Mar 2021, 18:03

Have you got any specific figures by chance? It'd be interesting to see how long runways are we talking about.

Max Land weight, F40, 1000 airport elevation, 29C, no wind, 2 Reverse, dry "Good" runway: 9200' Advisory Landing Distance. No Reverse? 11,000'
Going "Wet-Good" changes to 10,800' with Reverse, 14,400' No Reverse. Example of these conditions is Guayaquil (although sea level). Useable landing length approx 8450'

Having a statistically very bad day departing Quito, Ecuador at 175K with a deferred Engine Generator followed by the loss of the APU and remaining Generator? (low prob of course), Dry runway, 12,500' (1000 cushion), Wet-Good, 15,100', both with Reverse. No Reverse Dry? 14,200', Quito runway length is 13,445'. Guayaquil not an option.

My example over the Amazon on a rainy night? My previous equipment of 777,767,757 would involve a Split-S into Manaus and grumble about hotel rooms as I imagine all the Airbus series along with the 787/747. The MAX seems to require more runway than MAO would offer. I don't pretend to be an expert. I don't know what the reason is for the high numbers with that condition. Anti-skid degradation is understandable. There is a loss of spoiler capability as well and maybe a loss of the LAM (Landing Attitude Modifier) spoiler function may have an effect.

Long travel through the proverbial line up of Swiss Cheese holes, but someone usually finds a way eventually.