I recall reading about this a while back; my understanding it that any amount of engines with pax on board requires the flight to be conducted under ETOPS (ExTended range OPerationS). Freight with 3 or more engines does not require it.

GF,

Not necessarily true. Tis a fact, when it comes to engines, those on two engine ETOPS aircraft demonstrate a better record having less in-flight shutdowns or failures compared to engines on three or four engine aircraft. Some of this is advancement in engine technology but some is due to the extra requirements of engine maintenance and monitoring required to gain a 180 minute ETOPS rating. Engines are only part of the reasons for ETOPS. Other reasons for diversions include decompression, medical emergencies, observed smoke in the cabin or fire indication in the cargo hold. In twenty years, 1980-2000, 33 of 73 cruise decompressions occurred on airplanes with more than two engines. Diversion rate for aircraft causes or non-aircraft causes are the same for 2, 3 or 4 engine aircraft.

180 minute ETOPS approval starts with the airline meeting requirements of maintenance, training of ground personnel and flight personnel, training of route planners with an emphasis on suitable diversion airport for the aircraft requiring a diversion. This planning includes requirements to carry extra fuel for diversion purposes.

So it is more than just engines and when you think of it, how many routes in the world traveled by 3 or 4 engine aircraft would be affected by a 180 minute ETOPS requirement?

TD

ETOPS originally meant Extended Twin Operations. But, the FAA is ever "creative."

It has been known to mean Engines Turn or Passengers Swim.

Is it not possible that a pilot is more willing to shut down 25% of his power plants than one where it would be 50%?

Yes

Which brings up the terms of "hard" vs "soft" shutdown.
which make it even harder to sort out real risk from subjective risk.

I've had three shutdowns on four-engine airplanes.

1. KONT-PHNL: Turbine failure, shutdown, dump, return to departure airport.

2. PANC-RJAA: Slow loss of oil, have lunch and monitor, low oil pressure light confirmed by OP gauge, shutdown and continue 1.5 hrs to destination. Pinhole leak in oil line.

3. RCTP-RJAA: Loss of oil pressure after takeoff by 10,000', shutdown, continue to destination. Oil tank cap missing.

If flying a two-engine airplane, situation one would be no change, situation two would have been a diversion to an Aleutian chain airport and situation three would have been an immediate landing back at departure airport.

A four-engine airplane gives you more options, including continuing to destination for all the obvious reasons. The other thing to consider with a two-engine airplane besides ETOPS requirements is terrain enroute should an engine fail. Our two-holers had to fly different, more lengthy routes on some sectors than our four-engine airplanes.

I know I'm prejudiced, but I would much rather operate a four-engine airplane (and have since 1977) for the reasons outlined.

Edit: One also has the option of a three-engine ferry to a more capable maintenance base, which is not an option with a two-engine airplane.

Desert185

Agreed, I cannot make an argument that tris and quads are statistically safer (there isn't one), but they do offer more options and possibilities. One of which has been, and should remain, operations beyond any enroute alternate airports. Yes, trans-polar flights can be done in either plane, but I'd much rather shutdown an engine at 90N and be able to continue into Fairbanks than do so and be forced into Thule or Barrow or a Russian airport in winter.

GF

I believe the FAA must ensure that all airplanes on commercial operations whether twins, tris or quads are equally safe.

It appears we are fixated on the number of engines and the flexibility they offer when an engine fails.

Based on what I have read, it is my understanding that ETOPS covers more than engine issues.

I understand the FAA could not ignore the issue of tris/quads decompression enroute long-range operations and the resulting need for additional fuel reserves. (Remember Qantas 747 decompression and Manila diversion, luckily the incident happened close to an airport, imagine the same scenario on Sydney-Santiago!!)

I believe, similar to ETOPS for twins, ETOPS for tris /quads will require fuel planning for such eventuality (decompression). Airlines can address this by carrying additional fuel. If they do not want to carry additional fuel and forgo the payload then they will have to look for a suitable alternates enroute. Based on the limited knowledge I have on ETOPS, it appears to me that ETOPS greatly enhances the overall safety of all operations including those of tris & quads.

It seems it got redefined in 2007:

ETOPS - Wikipedia, the free encyclopedia

I seem to recall it being discussed here then - I think it was being called LROPS at the time. EOPS is a bit of a mouthful!

Maybe it's been said here before but I didn't see it. ETOPS for Tri and Quads are appicable to operations in excess of 180 minutes. This does not apply to cargo operations, just pax. Mostly in place for Polar Ops and maybe a few South Pacific routings. These Tri and Quad ETOPS do not exactly mirror Twin ETOPS so it is not a one size fits all template.

Spooky 2:

Check the link in my Post #31.

avgenie

Quads have to flight plan accounting for depressurization at the ETP, so it shouldn't be an issue. I agree ETOPS has, and will, improve reliability and safety for quads--better fire suppression, ETOPS=qualified engines and accessories, avionics cooling, etc. But, since twins HAVE to land at the nearest suitable airport in the event of engine failure, why are we extending that restriction to quads? They have demonstrated many times, that if planned correctly, can safety continue after an engine failure to the destination or a better alternate, esp. on trans-polar, trans-Siberian, and some oceanic routes.

GF

The present rules for three and four-engine overwater operations, taking into account three and two-engine ETP's, provides all the safety one needs without applying the imagined "safety enhancements" of ETOPS.

I am not sure if most of the airlines consider depressurization at the ETP. I am under the impression that ETP fuel is calculated based on an engine out. So most of the flight plans for A340/747/A380 would be based around 20, 000 ft (1 eng inop level off) rather than 10, 000 ft. (typical depressurization altitude unless extra oxygen).

Are you contending that air carriers can plan oceanic crossing with a "wet footprint" in the event of depressurization? I doubt that.

GF

gf:

Without a wet footprint would be much more desirable.:)

I can only speak of my limited experience in this reqard. I never flew International but I had a few years of flying the L-1011 from LAX to Honolulu, which is a very long over-water segment. San Francisco and Hilo were our deversionary alternates unless a problem happened with 300 miles of departure or arrival.

In the event of a loss of pressurization at the ETP we could indeed make Hilo or San Francisco at 10,000 feet without risk of a wet footprint. Or, we could make Hilo or San Francisco with the loss of one engine, whether we had pressurization or not. The diversion at the ETP saved about 200 miles, which is a fair about of extra fuel.