Can any airplane experts out there explain?
Recently I returned from a cross-country visit out west. The less said about the airport from which I left, and the crowds there and lack of decent signage, the better. And yes, wearing a mask almost unceasingly for close to twelve hours, all told (including long wait at airport and trip in bus from airport), is not the comfiest experience.
But the flight was great, and much to my surprise the pilot announced at the outset that we’d be arriving one hour early. And we did – exactly one hour earlier than scheduled. I know that when traveling west to east in the US there are tailwinds, but I thought those were factored in already. I also thought that if tailwinds were especially strong that day, the pilot would mention it as a reason we were making such good time. I’ve had that happen before.
But this pilot didn’t say a word about it. He was the laconic type.
Not only that, but I’ve never been that early for a flight landing because of tailwinds being especially strong – practically twenty percent early. What gives, oh you airplane experts?
And then, when we were getting off the plane, all its lights went out. It was very late at night and cloudy, and therefore the plane became nearly pitch black. I had been seated in the middle section of the plane and I was just starting to walk down the aisle to leave when it occurred. As I passed one of the flight attendants, she remarked that she’d never seen such a thing happen before. Clearly, the crew didn’t seem to be able to turn any lights back on, either, although people started using their cellphone flashlights to negotiate their exits from the plane.
I can’t find anything online to explain this. Why would the airplane lights go out like that? Why couldn’t the attendants turn them back on? Was this some sort of electrical problem? Or did the ground crew turn them off prematurely and is the crew unable to override that?
I know that someone out there has the answer. I’m counting on you, folks.
The airlines are truth-averse so you’ll probably never know.
That being said, I recently flew SFO to DEN and it was quite pleasant! I had heard there were insane delays over Christmas but apparently the problem worked itself out and we actually were only 10 minutes delayed. The delay was at the SFO (no surprise there) after we left the gate due to equipment failure/repair (which did not encourage confidence) but the pilot just pulled off to the side of the taxiway and it was apparently fixable there, after which we blasted off. I didn’t mind the mask; it was only on for about 3 1/2 hours, all told.
Once the engines are off, a land based power source has to be hooked up. It was probably delayed for some reason.
Maybe tail winds are more common in certain weather conditions. It is winter.
Sometimes the Jetstream is perfectly aligned, and really blowing. I once shaved an hour off a LAX-ORD flight. As for the lights, when the plane gets to the gate, they plug in external power and shut down the engines and perhaps the auxiliary power unit if it was running, to save gas. If the external power fails, it gets dark until power from some source is restored. I usually cranked the axillary power unit, since the noise would get the ground crew’s attention as well as turning the lights back on. 🙂 The emergency exit lights should have been available. If not, there was an electrical problem, or the crew made a mistake.
I would say it was more less traffic than anything. Lots of cancels makes ATC easier to deal with than before. If it was a wind factor, that would be a very strong Jet Stream, like 150 to 180Kt.
Mike K:
But there WAS power after we got to the gate, at least for a while. The first half of the plane deplaned with the lights on. The lights only turned off about halfway through the process.
I was on a flight from NYC to San Francisco and we made it in 5 hours. Groundspeed indicator on the entertainment screen was over 700 mph. My son is a pilot and checked the wind maps. While the jet stream does run west to east, there were very high winds running in the opposite direction. The downside was that once we arrived, the gate wasn’t ready. It didn’t eat up the entire time savings, but some of it.
The power outage in the airplane is easily explained. After landing and taxing into the gates, the crew starts the Auxiliary Power Unit (APU) to power the electricity at the gate after engine shut down. Either the Apu shut down or was not operating. It can take some time to hookup either a power cord or an APU on a tractor (Two ways of powering the airplane at the gate.) if the ground crew is not expecting to have to do it, it takes time for them to realize what’s happened and then time to get the power cord or APU hooked to the airplane. If the airlines are as shorthanded as they say, there might not have been enough manpower to get this done in an efficient manner.
As to arriving one hour early. There are two factors to consider. The jet stream is the most important. LAX to BOS is 2,611 miles. Most airlines schedule the flight for 5 hours and26 minutes. That’s about 474mph. Depending on the time of year the airline figures in weather delays and normal ground delays. If the airplane catches a 150-knot tailwind for
four hours of the flight. That gives a ground speed in excess of 624mph. Once at cruise with that tailwind you cover 2500 miles in four hours. Given some good breaks with no weather delays or ground delays, it’s entirely possible to arrive one hour early. And it’s possible the tailwind was even higher at some points of the flight.
I did the same thing in reverse on many flights. Heading west where the jet winds began at 28,000 feet, I would request a cruising altitude of 24,000. I burned a bit more fuel than the scheduled 36,000-foot cruise but arrived at destination as much as an hour early. The passengers loved it. The company hated it because I had burned an extra 500 pounds of fuel. When your scheduled fuel burn is 24,000 pounds and you burn an extra 500 to get to your destination on time or early, I thought it was good public relations. The bean counters didn’t agree with me. 🙁
Mike K has the right of it, I think. If the crew didn’t start the APU (Aux Power Unit) after landing and then shut everything down before the ground power was hooked up, that might have happened. It would be unusual to also turn the battery off, but maybe to conserve the battery, it wouldn’t power the lights. Some planes also have an essential bus, and non-essential bus. Sounds like a slip up by the crew.
As for tailwinds, the west to east jet stream can be very strong in the winter reaching sometimes over 150kts. So instead of cruising along at a ground speed of about 450kts, you’re up to 600kts. You can check the winds aloft here:
https://aviationweather.gov/windtemp
40+ years ago I had my PPL, then a low salary and family cut off my flying. Now spend probably too much time with flight simming. When I was at the air museum I became close friends with a retired Delta pilot who also spent his spare time simming. We had many good conversations.
Sorry J.J., looks like we were writing simultaneously. Didn’t mean to steal your thunder.
A long, long time ago, in a galaxy far away, I was an airborne radio repairman in the USAF. The radios went up in the planes, not me. Darn. When I went out to the flight line to work on a bird with a problem, I’d have to hook up the cable from the ground power unit to the bird and then start the gpu’s diesel engine. Don’t know if commercial aircraft still use them, but if the unit ran out of fuel, the bird went dark.
Time is part traffic, and a lot the winds. depending on weather, I recall the transit fuel load for a plane going from Houston to New Orleans was less that the load for the traffic patterns, ground taxi and reserve (in the case of SWA flights from HOU-MSY (NOLA), fuel enough to fly back to HOU or often to Dallas Love and vice versa, but often the load from MSY to HOU was quite higher due to winds and weather) It has been almost 20 years now since I read a full fuel load for a flight.
The blackout is likely the APU failed and ground power at the gate was also out, and the mobile unit(s) otherwise occupied or just not ready fast enough. Depends on the plane as well. I’ve seen airbus planes crash the flight computer and the plane need a full shutdown and reboot to go on the next flight but usually that doesn’t blackout the plane. The mechanic I knew refused to fly on airbus planes. Sadly Boeing seems to be going the same route in quality.
There is a tiny jet engine that powers a generator (the ramp is a very loud place because of them. small jets scream) and if it fails, or the main breaker for it trips, it will black out the plane. Also, this APU is often how they start the plane, so often when they are whonky, an air starter is needed to start the plane, and once and an engine is up and running, they use that to start the other engines.
Neo, from you description of the airport someone guessed LAX, which I thought of too. One of the worst airports in the World.
Not a pilot so nothing to add, I figured tailwinds.
On another not thread note, but aviation.
When my Dad worked a the FAA Long Range Radar facility in a CO city, I would go in to visit him at night (you could do those things then). One night he took me to the radar screens and said watch that dot. That dot skipped from on screen to the next, this was before the world knew about the SR71. But I found out that night.
Depending on weather, winds aloft can be much higher than “average”, and they’ll take advantage of this when they can for the fuel savings. I recall a Seattle-Phoenix leg last year where a strong low pressure system over the Rockies created enough of a tailwind to take an hour off the normal flight time (for only a 2200nm trip). I seem to recall a 130+ knot tailwind component that day.
For instance, today, there’s a strong low-pressure system over the Great Lakes, which could really push the jet stream along south of it. Winds aloft forecast for Kansas City shows winds out of the west at 118 knots for 39000 ft.
A typical single-aisle commercial jet might cruise at 450 knots for that altitude, yielding a 568 knot ground speed. On a more “normal” day, the tailwind might be expected to be 50 knots, yielding a 500 knot ground speed.
So, over a 2500 nautical mile leg, 500kts requires 5 hours point-point. 568 covers the same distance in 4.4 hours. Thus a full hour isn’t out of the question if the winds are right.
As to the lights going out – I’m not type rated in a turbojet, but my guess follows some others – they crew probably connected the airplane to ground power and shut off the jet’s Auxiliary Power Unit (a little turbine engine in the tail that can provide electrical power, cabin pressure, plus start a main engine) just before the cabin door opened. Then someone either popped a circuit breaker, kicked a cable loose, or maybe there was a fault in the cable. In any case, without ground power for lights, the APU would have to be restarted to get the lights back on in the cabin.
I concur with JP’s assessment on both time and blackout issue. If you know which type of aircraft, I can confirm a bit more. Neighbor across the street is an IP for Airbus and a good friend was an IP for Boeing 737’s and now pilots 777’s and 787’s. I know a bit more about Boeings. It is possible to turn off the emergency exit lights, which would otherwise come on in a power loss and at least help in getting down the aisle. Power loss is as JP noted, either the APU went out or Ground Power. Not sure why the pilots would turn off the emergency lights with passengers onboard, so they should have come on even in a power loss.
Also a little more on flight time; most scheduled flights retain the same anticipated takeoff and arrival times each day, which account for variable weather conditions. Airlines in recent years have tended to be conservative with flight times, because passengers missing connections is a risk they rather avoid. Finally, if you flew this past weekend with that front blowing through west to east, you likely had one hell of a tailwind along with a bumpy ride in the middle.
You have pretty good answers from several commenters here: tail winds and a problem with power on the ground. The pilot might have been counting on a Ground Power Unit that was unavailable when he arrived because he was an hour early! He should still have been able to use his auxiliary power unit (APU) in the tail, but all systems in aircraft have gremlins just waiting to interfere.
As for winds, you didn’t say what day you flew, but here in northern NV we had very strong wind Monday and Monday night. Wind speed over the ridge between Lake Tahoe and my little valley was over 100 MPH! It very likely increased with altitude, so it is entirely possible the winds at cruising altitude were super strong.
I moved to this valley specifically for those winds. When the wind is coming over the ridge at more than 25 MPH it often sets up mountain wave, or lee wave. Glider pilots (I’m one of those crazy people who flies WITHOUT AN ENGINE IN MY PLANE!) love to fly in mountain wave. I have been in a glider that flew for more than 12 hours in mountain wave, and have many glider flights of over 5 hours. BTW, when non-glider pilots ask me about flying without an engine, I tell them I don’t have to worry about engine failure, running out of fuel, or even fire being fed by fuel. Most are not convinced. Then I tell them about flying for many hours, or above 25,000′, and they usually take notice.
Aviation-Related:
Australia shut down nearly all airline travel for nearly two years with only a very limited domestic flight schedule left in play.
Now they’ve opened back up and there’s a leaked internal Qantas memo about the number of errors pilots and ground crew are making…. even very experienced pilots… having lost all Recency with the long furlough.
There was one case not so long ago where a commercial jet flew with the undercarriage locking pins still in place because ground crew forgot to remove them.
I’m inclined to give things six months to settle down when the air travel tempo finally kicks up here, too.
You didn’t say which airport you were flying to. In the 201Xs airlines started to add time to their schedules, especially busy east coast airports like LGA and EWR, because it would allow them to claim the flight was not delayed for statistical purposes. Low levels of traffic caused by COVID problems — fewer passengers, many flights cancelled because of the shortage of crews — meant that the flight did not need to eat into its schedule padding, Add a few more minutes for tailwinds and you get to an hour.
Does such a high-velocity tailwind as you folks are describing have any ramifications for the plane’s operation in flight? Any extra tricky turbulence or something like that?
Philip Sells:
I don’t know the answer, but I can tell you that the flight I was on was fairly bumpy for the first (western) half of the flight, and during that time it kept speeding up – or at least I perceived the engines being louder than usual and revving faster (if “revving” is indeed the proper word). The plane had a screen which purported to give its speed in real time, and it was definitely going faster than usual. It was between 630 and 670 MPH the whole time, but to the faster end of things on that first half of the flight.
I love these comments. So F is a glider pilot. So cool. Maybe I’ll put a glider passenger ride on my bucket list. I knew a hang glider flyer who would go on oxygen and fly for hours.
I’m no expert like some of the commenters. but I suspect that all the canceled flights in recent days may have had an impact on the flight time, as some have mentioned.
Even a little maneuvering for a landing queue will cause a delay. With lots of canceled flights maybe a straight shot to the runway can be assured. Plus, as JP K. mentioned the fuel load could be safely reduced and a little more altitude and speed can be accommodated. Also, was the flight full? Losing a few dozen passengers would lighten the load too.
TommyJay:
The flight was about 2/3 to 3/4 full.
NEO: This is one of the more interesting posts I’ve seen (although I find most posts on here to be very interesting). I have a pilot friend (Airbus) and we email lots about his experiences. I find it fascinating. So thank you, Neo, for the post, and a YUGE thank you to all the commenters ! APU’s and the jet stream ! How ’bout that. I wonder where you find wind speeds at 35,000 feet !! I’ll have to ask my friend. : >)
Yes, I’ll vote for a lightly loaded plane, low traffic at the destination airport, and a good tail wind.
Neo,
You don’t have any vague memories about bug eyed , little green aliens and fading in and out of consciousness , do you? 😉
@JonBaker:
“..vague memories about bug eyed , little green aliens and fading in and out of consciousness..”
I hope this clip doesn’t give anyone present any kind of traumatic flashbacks.
Independence Day (5/5) Movie CLIP – Russell Becomes a Hero (1996) HD
https://youtu.be/NyOTaHRBTXc?t=92
PS: You might want to watch this sitting down, Om.
Zaphod,
That was a good movie.
@JonBaker:
It was!
The scary part is that seems was just yesterday that I watched it in a cinema which is no longer where it once was.
Perhaps relevant (this is the first thing that pops into my head when hearing about flight time differences that depend on flight direction — which, it turns out from reading the above, is not correct):
I’ve sometimes ask myself, as have many others, I’m sure, the following question:
why can’t a plane that is travelling west (opposite the earth’s spin) simply take off, accelerate to “scrub off” the speed that it has from moving along with the surface of the earth when it was on the ground, and then simply maintain enough speed to stay in the air (which I assume is less than the typical air speed of ~500 MPH), letting the earth rotate at ~1000 MPH (near the equator, at least) underneath it?
I’ve looked around at physics sites on the web and haven’t found an answer that I actually understand. One site compared the situation to a ball dropping from a high tower and landing at the base of the tower rather than some distance to the side of the tower. To which I reply “sure, but a ball doesn’t have a jet engine it can use to change its speed relative the earth’s surface”.
I’ve settled on the thought that the atmosphere is also rotating along with the earth’s surface (and often, as described above, considerably faster than the surface) so that any benefit one would see from flying west is overwhelmed by atmospheric motion.
I’ve never seen the question answered this way, however, so it could be entirely wrong.
I do think, however, that if we were on a planet with no atmosphere, a rocket could go up, establish a speed differential relative to the surface (a one time acceleration) and then simply apply enough thrust vertically to stay airborne while waiting for the desired destination to rotate beneath it.
The trouble with the thought in that last paragraph is that it doesn’t matter which direction (with the rotation or against it) the rocket goes. Frames of reference give me a headache.
“Frames of reference give me a headache.”
Tensors to the rescue.
Now you have a bigger headache.
It is my apocalypse.
Philip Edwards: “I wonder where you find wind speeds at 35,000 feet !! I’ll have to ask my friend. : >)”
As I posted above you look at the weather charts and plan the flight accordingly:
https://aviationweather.gov/windtemp
deckhand: yep, the atmospheric rotation is the same as the earth’s. The winds aloft and storms are just “eddies” in a general motion of the atmosphere. Akin to your idea: why are space facilities in low latitudes, ie Cape Canaveral, Vandenburg, etc ? Left as an exercise for the student 🙂
Philip Edwards:
As I posted above you look at the weather charts and plan the flight accordingly:
https://aviationweather.gov/windtemp
Note the sliding scale for altitude selection which should be set to the intended cruise altitude. If you slide it lower, you’ll see slower windspeeds due to boundary layer effects. That’s due to the friction the air has with the Earth’s surface.
Air is a substance. Technically, it is a gaseous substance, but for aeronautics, it is easier to think of it as a fluid, because it has mass and density that flows like a fluid. If you get into a river; you can float and let the current take you in whatever direction is downstream. But if you want to go upstream, even if that direction is east, you can’t just overcome the speed of the current and let the Earth’s rotation take care of the rest. Well you can, relative to the sun and other celestial objects, but not relative to the Earth’s surface. The air isn’t as dense as the water in the river, but to the aircraft, the situation is exactly the same as you in the river. The only advantage is as physicsguy notes; wind does tend to flow in the same direction as the Earth’s rotation, while water flows in the same direction as gravity. Air even has eddies like water flow, and just like with water, the eddies can be quite dangerous.
Neo@8:33pm: “ It was between 630 and 670 MPH”
Converted from statute MPH to Knots = 547 to 582. Assuming a 450kt cruise, that would suggest tailwinds of 97 to 132 knots.
Anytime you have a swift river of air aloft that is adjacent to an airmass that is slower or moving in a different direction, turbulence is more likely.
Finally, heavy jets at those altitudes don’t have much of a speed window for the pilots to work with. Air density decreases with altitude, thus a heavily loaded wing needs to move faster to generate the same lifting force in ever thinner air. Weight is a key factor here. On the other hand, the speed of sound lowers as altitude increases, so the max speed possible is limited by transonic effects. At some altitude, these two speeds converge, which limits the useful altitude one can climb to. Thus, there isn’t much of a speed margin at turbojet-efficient altitudes.
If your grandchildren are in L.A. and you’re in Boston, you have my sympathy. I assume you’re implementing a long-range plan to persuade your son to take his family back east. Best of luck.
Neo wrote:
“I can tell you that the flight I was on was fairly bumpy for the first (western) half of the flight, and during that time it kept speeding up – or at least I perceived the engines being louder than usual and revving faster (if “revving” is indeed the proper word).”
The first half of the flight would have been over mountainous terrain, where the wind is flowing up and down (relative to the earth). That’s the bumpy part.
The changing engine RPM is due to the auto throttles on the aircraft responding to that up and down motion. When you’re going up, the auto throttles would have slowed the engines down. When you’re going down, the auto throttles would have sped them up to maintain altitude (and energy).
Biden’s energy policy.