The Great Ongoing Aviation Thread (general and other)

Miscellaneous and Personal Stuff I Must Share
5663

Bird strikes …

The key thing to recognize is there is no dedicated maintenance staff inspection of the airplanes overnight. At least not at non-hubs, which describes STL for Delta. Why not? All those maintenance jobs were eliminated 10-15 years ago in the name of cost savings = low fares.

So the first person to look at the aircraft critically is the First Officer when they conduct their pre-flight walk-around roughly 30-40 minutes before departure. The baggage load crew may notice something huge like a mashed wingtip hit by a catering truck, but that’s about the extent of their skills / interest. They’re real good at looking for dents immediately around the cargo doors because they want to see and document those before they begin loading so they don’t get blamed for them later.

Some carriers require that the crew that leaves an airplane to sit overnight at a non-maintenance station make a quickie post-flight walk around looking for, yep, bird strikes, flat tires, & fluid leaks. Which if found need to be documented with HQ so HQ can arrange to work the problem overnight. I don’t know if Delta does that.


In any case, as @Richard_Pearse says, once evidence of a bird strike is found there are no more decisions to be made. It absolutely positively gets documented with HQ, and the airplane is stuck there until a maintenance crew can get there, inspect it, determine what needs to be done, etc. Sometimes that’s just look at it, determine there’s no damage, wash off the remains, document the work and then the airplane goes. Sometimes it needs an engine or a wing flap replaced, which is the work of a couple-three days.

As to the fact the plane flew in that way …

The strike may have occurred just before landing. Birds are typically a near-the-ground problem. If the bird went into an engine, it may well be the engine would run adequately enough at near idle that the crew didn’t notice a problem, but the engine would fail the first time it was cranked up to takeoff thrust. That’s worst case, but it’s a bad enoough worst case to be well worth avoiding.

Not even remotely. We would routinely delay flights from mid evening until tomorrow morning, 10-12 hours. By “routinely” I mean several every single night just at my one hub. And more like a couple dozen on any/every night where the thunderstorms were in our shit from 6pm to midnight.

The gotcha is that DOT reliability statistics track “delays” differently than “cancellations”. So the carriers are strongly incentivized to not cancel a flight if at all humanly possible. Delayed 9, 24, or even 36 hours is scored exactly the same as delayed 16 minutes. Cancelled is a much larger black mark than a delay regardless of duration.

I would really like to see that loophole closed and the gamesmanship stopped. Not gonna happen.

5664

Thanks to everyone for the explanations. I have to fly in and out of Lambert monthly. It’s very obvious that so many services at that airport are contracted out and being done at a bargain-basement cost. If there are no unexpected problems things are fine. But if there are mechanical issues they have to bring in parts or even people from another city to fix them and you will be waiting multiple hours: this has happened to me three times in the last six months. And if you’re arriving it takes 45 minutes for your bags to hit the carousel: the baggage services are contacted too and don’t seem to have enough staff to do the job efficiently.

Appreciate the responses!

5665

I’m surprised the 737 has such a high landing speed. I expect an unwritten design goal is to keep the speed as low as possible.

Do any of the landing systems use a FLIR system? Getting lined up on short final seems fairly academic in IFR. But keeping the wings level and the nose aligned in a crosswind bumps things up considerably. Is the system designed to align the main gears to the runway centerline or the cockpit?

5666

The problem with the 737 is the airplane was built with short gear legs so it sat low enough to the ground that no tongue loaders were needed for baggage loading and a short built-in airstair could be installed to load passengers.

Because in 1964 the idea, especially in Europe since Lufthansa was the 737 launch customer, was to use the then-tiny 85 (!) passenger 737 mostly at austere GA airports with no servicing infrastructure. It was to be the RJ of that era.

That idea was quickly abandoned as stupid, plus a lot of small airports grew quickly in the early years but the now 200-passenger airplane has been cursed ever since by being built too low to the ground.

The short gear legs limit the touchdown attitude to a few degrees lower than taller airplanes. Even given the most amazing high lift devices possible, the only way to lower the approach and touchdown attitude further is to keep the speed up and the AOA down.


No airliners use FLIR … yet. It’s been talked about, and some bizjets have it now.

As to centerline tracking, all airplanes put the localizer antennas back near the main gear. So what’s really tracking the beam center is those antennas which put the main gear in the same place they are. In a crosswind the cockpit ends up offset a few feet one way or the other.

The general approach to landing an airliner in a crosswind is to fly a crabbed final and maybe (or not) remove some not all crab just before touchdown. For very low-vis approaches, the wind limits are 15 knots crosswind component which is not that much compared to the speed of the airplane. So the crab angles aren’t bad.

In the case of a limit low vis and limit max crosswind situation, just prang it on in a crab; the gear can handle it and you do NOT want to start drifting or waffling around when you can only see a couple hundred feet forward and may not even see both runway edges.

5667

So when you land on a crab, how quickly do you have to straighten out? Seems like the wind load vs. tire friction would mean PDQ?

5668

United and Boeing must be breathing a sigh of relief there’s finally an aviation story not about them.

5669

Something very surprising:

If this becomes a trend no one is going to say anything to investigators after an airplane accident without a lawyer/taking the 5th–remain silent so as not to incriminate themselves.

5670

OK, now it makes sense. Thanks.

Before I finished reading that sentence it dawned on me where they would mount the antenna. I’ve probably washed a few of them back in the day.

I’m glad they’re considering the FLIR system. Seems like cheap insurance.

5671

When you land a big airplane in a crab, the velocity vector of all that mass is aligned with the runway even though the fuselage is not. Real quickly after the wheels hit going sideways from their POV, all that inertia forces the airplane to align the nose with where you’re going. A dab of appropriate rudder doesn’t hurt, but isn’t really necessary.

In nicer weather it’s polite to take out some crab in the flare and land in a partial crab / partial slip with some yaw rate towards alignment still in progress at touchdown. Ideally … on a good day … when your shit is strong.

Bottom line being that post touchdown fuselage alignment with the runway is going to happen very close to instantly whether you help or not.

That is indeed a very worrisome development if true.

If it turns out Boeing management conspired to create an environment where workers were expected to lie on paperwork and cut corners, the managers belong in jail and the workers need to demonstrate they can re-learn to be quality-oriented when placed back in a quality oriented milieu.

OTOH, as you suggest, if this is just a witch hunt aimed at the workers, we can kiss safety goodbye throughout the industry. CYA will become the order of the day.

5672

Reluctant Rudder syndrome? NTSB and Boeing are looking at:

There have been 3 incidents of this issue, all caused by a disabled rollout servo becoming stiff after a cold soak. It becomes an issue after touchdown, when rudder hydraulic control pressure is substantially reduced. The most likely reason is lack of use and maintenance, as all the instances have occurred on airlines that have disabled the rollout feature.

Houston runway excursion:
That was due to taking the turn at 30 knots during high speed taxi. ATC had asked the crew to expedite their exit of the runway, as another aircraft was inbound. So they accelerated and misjudged the turn.

Also this is the 5th incident for United Airlines in the last month.

5673

ATC asked for high speed to the end of the runway after the crew asked if they could go to the end. I think the initial expectation would have been that the 737 vacate via one of the rapid exits, then the crew ask if they can roll to the end and ATC approve on the condition they make it quick, then the crew balls up the turn at the end.

It’s a difficult situation to be in because it relies on you using judgement in a way that you don’t normally have to and therefore aren’t particularly well practiced in.

Normally when you land you would be aiming to vacate at one of the standard exits partway along the runway. You might have done a landing performance calculation to work out which auto-brake setting to use or you make be lucky enough to fly an aircraft with “brake to vacate” where you can tell it which intersection you want to vacate the runway at and it will modulate the braking to achieve it, or you might just know that low brakes works ok. You land, you slow down, you disconnect the autobrakes and taxi off at the appropriate intersection. Worst case you miss the intersection and take the next one. If you’re landing on a short runway you apply enough braking to ensure you are down to taxi speed well before the end of the runway. All quite straight forward and requiring minimum judgement.

It’s more difficult when you’ve been told you can vacate at the end of the runway but you need to go high speed to get there. There’s no backup if you miss the turn off, there’s just runway over-run area and grass, meanwhile in the back of your mind you know someone else is snotting down final at 150 knots and ATC are wanting you to hurry up. You’re having a normal relaxing day and then suddenly the end of the runway is coming up and you’re still doing 50 knots and are struggling to get slow enough to make the turn. Before you know it, you’ve over-run a 10,000’ runway in a medium sized passenger jet.

5674

FedEx are using FLIR as a part of their enhanced vision system. It makes sense for them as they do a lot of flying at night. They’ve had it for a long time so one can only assume it’s not being rolled out to passenger jets because the executives don’t see a compelling case for it just yet.

I’m happy to take credit for it, but I think that was @Llama_Llogophile.

5675

Which is better than our mins with autoland for CATIIIA of 175/175/175, however, with no failures we are CATIIIB which is 75/75/75 and no DH. We don’t need to do them for aircraft equipment proving any more so we generally only do them a couple of times a year for real plus the standard sim practice.

5676

Thanks and also for the image. Now I know what to look for.

5677

More troubles for United with their fourth emergency this week. But huzzah! Just for something completely different, finally – finally! – it’s not a Boeing but an Airbus A320 that’s the culprit.

5678

@smithsb: Thanks for the round-up on causes of these screwups.

“Unable” is the single most powerful word in a pilot’s vocabulary.

What’s doubly stupid about this one is that the airfield layout is such that zero distance, and only trivial time, is saved by rolling to the end. Had they cleared at one of the high speed offramps as is typical, they’d have taken the same route to the ramp area.

The only savings available, of just a few seconds, is being able to stay a little faster on the runway a little longer. But not too fast too long or you get what they got. Oops.

The airplane that’s on the runway owns it until they’re off it. Take the time to be safe; if you’re pushing it, you’re f***ing up. Period. You’re responsible for your airplane and your flight, not the other guy’s. Never confuse your priorities.

Easy to say, sometimes harder to do.

Wow. I did not know that. Thank you.

The key insight here is this proves there is a system certificated for Part 121 use on big jets. That pic is a 757. The future is coming.

5679

Hoping this is the right thread for this question.

I live and work near John Wayne Airport (SNA). Most of the time, the planes take off or land to the south(west), out over the Pacific, but sometimes, when the wind is from inland (ie, the Santa Anas), they take off and land into the wind, to the north/east, which typically means a dry, blustery day.

Yesterday, morning, I noticed a plane taking off to the northeast, which surprised me because I had just seen planes on their normal landing approaches (toward the southwest). Then, five minutes later, I saw planes taking off in their usual direction.

I always assumed this pattern was pretty fixed - they go one way or the other for long periods. I’d imagine that for taxiing they’d want it consistent, so all the plane are moving the same direction on the ground.

Who or what decides which direction to take off for an individual flight? What might have made that one plane take off the opposite way from the others that hour?

5680

When you say “morning”, what time generally do you mean? SNA has a hard curfew in the very morning, where nobody may depart prior to IIRC 7am (or is it 6am?). Too busy to look it up just now.

If you were seeing that takeoff right around that time, so this was the very first airplane of the day to take off, all kinds of one-off details could explain that.

If you’re talking mid-morning amongst lots of other departures going the other way that’s a totally different scenario.

5681

I was almost going to tag you as I knew you’d know, LSL.

It was around 915AM Sunday when I saw the “wrong way” plane. What was odd was that around 920AM, the planes were arriving, and leaving, the “normal” direction, and I am pretty sure I saw normal takeoffs and approaches earlier in the day.

SNA takeoffs start at 7AM (maybe 8 on Sundays), and they start taxiing at 645 to get in line. As I leave my neighborhood for work, I can tell it is going to be a dry, windy day if I can see the takeoffs going toward the mountains (as opposed to the ocean). That normally doesn’t last all day, though and they go back to normal.

I feel like this was someone screwing up, which is unsettling as a regular user of SNA, and one who works under the normal approach path (I can hear them landing toward the southwest as I type this).

5682

At what point does the Boeing drama warrant its own thread?