A 737 almost tail strikes and stalls on take off.
I'm no pilot but it seems to mean the pilot did not deploy flaps.There is an alarm that goes off if the throttle is increased too far and flaps are not deployed, but it can be disabled by pulling a circuit breaker on some airplanes. There was a Northwest crash in Detroit that was a result of this happening:
I only fly light airplanes and there is no alarm related to the flaps. Most light airplanes takeoff without flaps, unless the runway is very short or there are tall things off the departure end.
The slats are deployed. It looks like a small amount of flap as well. I don’t know enough about the B737 to comment on whether that is a take-off flap setting or not. As mentioned above by Desert Nomad, there is a warning if you increase thrust without the flaps at a take-off setting. An Emirates A340 did something similar out of Melbourne. They entered the wrong weight into the flight management computer and all speeds and take-off settings were based on this (lower) weight. When they tried to rotate they found it wouldn’t fly. It didn’t get airborne until ~150m past the end of the runway.
This makes me think that the airlines are still using the absolute minimum power to get airborne as possible.
Aircraft type, weight, Wx conditions, noise, etc.
The famous Air Florida crash into the river, etc. seems to have not caused a reliable way for the pilots to have a go - no go that is somehow attention getting about the lack of acceleration/airspeed/etc. for that takeoff other than seat of the pants and personal experience.
Also, back in the old days there was max continuous power, METO ( max except take off ) etc. What can the modern jet engine handle with regards to manually going to full power or more power without causing damage?
When the pilots are so pressured into saving every penny so there is a profit that it causes actual interference with safe operation by causing them to apparently be unable to realize/identify and ACT in these kinds of situations?
Why no computer, gizmo, warning light that tells them to add power or abort?
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[RANT…]
I understand why they fly the margins so close but since they ( pilots) are wholly responsible if anything goes wrong, why are they still so instilled with the ‘do nothing’ attitude? Because if they burn 200 more pounds of fuel ( number pulled from my ass as I do not know fuel burn rates on Big Iron ) more that they were supposed they will be on the carpet or all the way to fired?
Are the cost benefit numbers so great as to be able to write off 100+ deaths, an aircraft destroyed, bad press and lawsuits that it is more profitable to take the occasionally crash even when there is a known fix?
[/RANT]*
Since the pilots’ lives and careers are on the line, why don’t they just blast max engine power during takeoff and be safer? It’s not like the airlines will audit their engine readings afterwards to check to see if they were using more power than they had to…right?
Yes and no. It is standard technique to use reduced power (“flex”) for take-off. In our company we are advised to reduce thrust as much as possible (it saves engine wear but uses more fuel by the way). This doesn’t necessarily mean there is no margin left though. There is a limit to the amount we can reduce thrust, and if we go down to this limit there is often still a significant buffer between the weight we could take off with and the weight we are at.
Personally I will not intentionally reduce the book margins to zero just to be able to flex the take-off. I like to have some buffer between our actual weight and the weight the thrust setting is calculated for. I think this mindset is common but I haven’t done a poll or anything.
The Emirates incident referenced in my previous post resulted in the ATSB (Aus version of the NTSB) recommending that systems be put in place to detect less than expected acceleration and gross errors in data entry. Manufacturers are working on the problem but I don’t think there’s anything in play yet.
5 minutes at max take-off thrust is a fairly typical limit. Note that you could do this on every take-off and you wouldn’t be exceeding any limitations, but if you only did it on one take-off in a year and went to 6 minutes rather than 5, the engine would require an inspection. Doesn’t really make sense, but that is the limitation.
Max take-off thrust is not full thrust, you can further push the thrust levers up to the firewall and get more. This would only be done to escape windshear or avoid hitting a hill. You’d only do it for as long as you needed to and the engines would probably need an inspection before next flight.
Well, given somewhere around 100,000 flights a day world wide, and the relative lack of take-off accidents due to a lack of thrust, the numbers would suggest that this problem, if it even exists, isn’t a priority. At the moment, it seems that a loss of manual flying skills is the main problem for the industry. That is what is causing accidents.
Well, those audits do happen. No one would know if someone used max thrust occasionally, and in our type we have to do it every now and then to validate the engine’s ability to produce rated thrust, but if everyone did it all the time, management would know pretty quick.
That said, what if I told you that using max thrust caused a significant increase in failure rates? You’d just be replacing one problem with another.
Personally I don’t see a problem here. I think the vast majority of pilots are taking a middle ground and reducing thrust to a point they are comfortable with. The Emirates incident was caused by a pilot under stating the aircraft weight by 100,000 kg, that’s more than 25% off the actual weight, and the aircraft still managed to get airborne. It seems to me that the margins in place, when applied correctly, are fine. It takes a gross error to get close to an accident.
Finally, with regards to the B737 in the OP, they may well have been at max thrust, lots of thrust doesn’t do much good if you have the wrong speed/flap combination.
I had to look it up, but the 737NG has 9 flap settings: 1 fully up, 4 for takeoff under various conditions, and 4 for landing also under various conditions.
The engines also have between 2 and 5 max thrust settings depending on the factory options chosen, plus the continuously variable “flex” feature described above by Richard Pearse.
In the YouTube vid we can clearly see the leading edge slats are extended. We can also see the trailing edge flaps are *slightly *deployed. Which implies they are set at either the “flaps 1 degree” or “flaps 2 degree” position. Either of which would be completely normal takeoff settings used every day around the world for certain combinations of weight, power, and runway length. So there would not be a warning horn about that flap setting, nor would we expect any failure in that horn to have any impact on the day’s events.
My interpretation is that somehow they got the wrong speeds vs. flap settings. Getting that right is a multi-step process:
- Obtain the accurate aircraft weight from HQ & the load crew.
- Enter the appropriate manual tables, tablet computer apps, flight paperwork, etc. to determine the appropriate speeds and corresponding flap settings (Typically there are several combinations that work, and policy will dictate which to prefer in that case). Make no mistakes in this convoluted process.
- Correctly dial or keystroke those intended speeds (there are 3 or 4 for each takeoff) into the aircraft computers for display on the airspeed instruments.
- Correctly deploy the flaps to the intended setting.
- Read the airspeed and flap indicators correctly (and your notes about the step 2 results) during the checklist to ensure they’re set as intended.
- Read the airspeed indicator correctly during takeoff roll.
Somewhere in that chain they or somebody else upstream of them goofed. They ended up with too little flap setting for the speed at which the pilot pulled back on the yoke to lift off. Or equivalently they ended up with too little speed for the flap setting in effect when the pilot pulled back on the yoke to lift off.
Every item in that chain of 6 steps has been goofed up sometime by somebody somewhere. Nothing more can be said about this particular event with any certainty.
This does not appear to be a case of too little power. But that opportunity to screw that up is out there too. The correct flap setting and correct speeds will only ensure liftoff within the runway available if the correct power is used.
Sorry to double-post. Last night I addressed the OP. It was too late to give Gus’s post the attention it deserved. So this morning I’m coming back to speak to it.
Returning for a moment to the OP: At very low flap settings such as were used in the Youtube, per our manuals the normal clearance between the tail skid and the runway on a correctly flown 737 takeoff is 13 inches. On a machine 130 feet long and 40 feet tall. As applied to the video, we see the tail skid got about the right distance above the runway but liftoff didn’t occur as expected. It was good piloting at that point to not continue pulling and drag the tail. Instead, after a moment’s confusion they lowered the nose, continued to accelerate then tried again. With a certain amount of bobbling as they were feeling for what to do next in an uncertain but rapidly changing situation.
You’ve mixed a bunch of issues here.
Air Florida failed to get airborne because they didn’t know they’d iced up the engines and they ended up setting only about 2/3rds of the power they thought they had set. So they had a massive shortfall from what was planned. Yet they still got airborne … barely. Had that not been Washington DC with the need for an abrupt aggressive turn immediately after takeoff, they may well have flown out of the problem with the existing thrust, or recognized the crappy performance and shoved the throttles up further and flown away uneventfully. As it was, they lifted off, cranked it into the turn, and fell out of the sky all within about 20 seconds. Oops.
One of the industry responses was to emphasize the fact that depending on the aircraft type there are 4 to 6 instruments per engine associated with engine performance. All of them tell a story about thrust output. Setting the throttles so the master instrument settles on the preplanned setting and ignoring the rest is bad. That’s what Air Florida 90’s crew did.
Setting the throttles so the master instrument settles on the preplanned setting and checking the rest of the gauges for expected ballpark values is good. Note the setting, settling, and cross-checking can only happen in an about 5 second window as the airplane accelerates. Tweaking the throttles later usually means unplanned and undesired thrust reduction.
The deep underlying problem that day was a startup airline with crappy training, crappy standardization, and crappy 3rd rate crews. Many of whom had only a couple months’ experience in airline ops. But the fares were low and they were a media darling at the time. If you want to rant, rant about that.
You are 100% right that having a reliable acceleration check would be real nice. And doesn’t really exist today. The reason it doesn’t is physics. The opportunity to stop safely is when you’re real slow. Above a mere 80 knots, roughly half of liftoff speed for most jets near their respective max takeoff weights, we consider a rejected takeoff to be a very risky maneuver done only for an immediate and clear concern that it won’t fly at all if we continue. The problem is the acceleration characteristics of jet engines, vagaries in rolling takeoff technique, gusty winds, etc., leads to the reality that the acceleration shortfall, if any, will only become unequivocal fairly late in the process. Well above the 80 knot cutoff.
This thread http://boards.straightdope.com/sdmb/showthread.php?p=17935504#post17935504 starts on another topic but at about this post, and especially by #44 it mutates into a pretty good 20-plus post discussion of transport takeoff performance and thrust setting. It warrants a quick read. I won’t rehash it here.
Bottom line: Using less than max thrust for takeoff is a safety enhancement, not a corner-cutting exercise. The statistical outcome is far fewer very dangerous engine failures. In exchange for a few more close-ish calls with inadequate performance due to bad data, bad calculations, or bad piloting. These short-falls can often be fully remedied by simply shoving up the power.
Here’s a bigger picture look which does partly support your rant:
Traditionally aviation has used the mantra “measure it with a micrometer; mark it with a crayon; cut it with an axe”. With the result that the tools used to figure the micrometer settings have a hefty fudge factor to allow for the axe’s hefty kerf.
As aviation gets ever more computerized there is a risk that IT engineering types increasingly believe we can “measure it with a micrometer; mark it with a laser; cut it with a laser”. And so therefore reducing or eliminating the fudge factors is both cost-saving and safe. Pilots, including pilot management at sensible carriers, are fighting a rear-guard action against that gathering attitude.
There’s no raging fire here today, but there is a faint wisp of smoke from some smoldering tinder. This applies to all aspects of aviation operations and training, not just takeoff performance.
Thanks LSLGuy. I am learning a lot from you & Richard P.
It seems as with the increase in big iron size and loads that reliability is becoming an absolute requirement. One reason is the lack of long enough runways which is really not fixable in the short or long term.
In the small stuff I flew, ( say like a C-310 ) there is a time when your best choice is to keep flying. Those were very seldom from most airports/conditions and even more rare while still on the ground part of a departure. What it seems to me to be now is that 99.9% of every big iron takeoff you are committed to go when nothing is wrong other the fact that you are trying to take off from an unsafe place for that particular aircraft. Every time !!!
OK, I reread from Post 30 to the end of that thread and you were correct, I needed to reread it.
*[rant]
Another rant, not expecting a response.
So, it seems that there is a point where spending more time & money is not worth it due to the low death count. it is not cost effective. We see this all the time in the personal ground transport areas.
But…
In airline people transport sized and bigger aircraft, driven by professionals who are specially trained, tracked, monitored, etc. that safety takes a BIG backseat to complaints about noise that was there before the houses were built, ground that is too valuable and will not be used for safer airline needs but for more houses to be built for more people to complain about the noise that was there first, and on and on.
It seems to me that the industry is doing all it can/wants to under the constraints imposed as noted in the other thread.
In all my flying, I never allowed myself to be in a position I did not have a choice in nor a place where 99.999% luck was necessary for survival. Any time
If I took risks it was a conscious choice and I always felt that other than an act of God, I was able to overcome anything that happened. I am old now because I could and did do that. And I did some really apparently stupid & dangerous flying with full malice of fore thought. But I never allowed my self to be put in a situation where 99.9999% of every takeoff required luck to be completed safely. The record speaks for itself that transport aircraft of today has a great safety record.
But
I can’t help but note that I flew in marginal aircraft in bad places under bad conditions and am old. God did not smite me but those damn gremlins sure did a time or a hundred. And I flew out of them, or thought my way out of them, killed no one, and I personally did not make any aircraft unusable. Was a passenger in a few though. Arrogant and jaded pilots are a PITA if not totally deadly.
Roads are rammed though, land forced to be sold so they can be built and on & on. Yet, the safest, most regulated, highest tech form of transport has it’s safety controlled the most by the least informed. There are well known fixes for all the major problems of air transport but the industry allows those who… Gah, just another rant… never mind… My notions of personal responsibility are no longer valid in 2017.
As long as we force larger & larger & heavier & heavier aircraft to use the same length runways as used 40 years ago, the margins are going to get smaller and smaller and no one who is …
I am just glad I got to fly in the days before I had to push button"C" because it was button"C."
[/rant]*
You make some good points here. It’s not quite that black and white, but your well-honed instincts are barking up the right tree, if not IMO the right branch.
At someplace like DFW where we have 4 runways each 13,000 feet long (plus 3 more around 9000’) most jets most days could get airborne, climb to a hundred feet, change their minds, nose over, and land on the same strip stopping before the end. Utterly against procedures, and more dangerous than other courses of action, but physically doable.
Conversely, at LGA, MDW, DCA, SNA and a few others, the margins are very small for most takeoffs and landings. In fact we often have “buy” some margin by leaving people, cargo, or baggage behind when there’s just not enough and nowhere else to find any. In extreme cases we “buy” margin by leaving off fuel & stopping to get more along the way. This isn’t true for every airplane every day, but it is true for almost all airplanes on certain hot or snowy days.
To be clear, even when we’ve done the math and the weight, winds, temps, and runway length all point to “It’s a total squeeker; we can’t take one more waffer thin mint without being overweight”, that still means we can accelerate to just below V1, lose an engine, and stop safely on the runway without setting fire to the brakes or tires. Or equally, that still means we can accelerate to just below V1, lose an engine, and take off in the remaining runway and climb adequately to overfly any and all obstacles, including nearby mountains.
We are never in that ugly corner common to light piston twin ops where you’re too fast to stop *and *too slow to go, or else too hot/high/heavy to climb out of ground effect. We’re simply *never *there. Never. (Abarring screw-ups with the loading or calcs.)
As the situation gets closer to being a squeeker what *does *happen is the slack available to account for less than Yeagertastic piloting gets *real *small. If you’re just not good enough, or complacent, or a momentary stray thought pops into your head at the wrong moment, **and **today’s the day Fate drops a turd in your punchbowl, some folks will discover that it’s more than they can handle. Cue CNN.
Said another way, a particular failure under particular conditions that would just be an extra-interesting day at work at DFW would instead be a severe life or death test if the only difference was it happened at LGA instead.
Going to the big picture rant.
We in the US are indeed at the place where, due to the impracticality (read as tax dollar cost and NIMBY opposition) of building adequate airports for the traffic and aircraft size, we’ve got places where safety is notably weaker than at other places.
Sometimes, like LGA, SNA, MDW, and DCA it’s mostly a matter of too-short runways. At other places like SFO, STL, LAX, and most of ATL, the problem is runways too close together where ever more “creative” traffic flow procedures are invented to push ever more traffic through the same facility. LGA, ORD, CLT, MIA, & SFO also have runway arrangements that result in gamesmanship to interleave crossing streams of traffic. ORD is now spending 15 years (after 25 earlier years of political wrangling) and $7.5 Billion (so far) modernizing their runways’ layout from the WWII standard random pile of overlapping pickup sticks to the modern layout of 6 or 8 widely spaced parallel runways.
In one sense it’s silly to find ourselves here. If we could close LGA, SNA, MDW, and DCA to anything bigger/faster than a turboprop the total takeoff & landing accident rate for the major US airlines would be cut significantly.
We keep inventing safer & more capable airplanes, then “spending” some or all of that advance not on actually improving safety, but instead improving system throughput. Kinda like installing anti-lock brakes on cars then folks start driving more crazily.
At the same time, airline safety is so tremendously good, and still improving, that we are very, very far down the curve of diminishing returns. Pursuing more safety just for safety’s sake may be silly too.
Most of society seems pretty happy with the current tradeoff. Although if you ask them directly you get different answers depending on what specific question you ask. More safety? We’re all for it! At more cost? Wait, not so fast!
As to me I’ll repeat something I put in one of my first posts at the 'Dope. I hope to retire *from *work, not get killed *at *work. As long as the public has an irrational fear of airplane crashes they’ll agree to “over”-spend on safety vs. a more rational decision process. Which is fine by me.
Another thought:
“Professionalism” is getting the job done right over a career despite the obstacles. The specific details of how you professionally drive a Boeing in and out of LGA all day and how you professionally drive a C-310 up in the flight levels on very precise parameters despite primitive tools and craptacular maintenance are very different. But the fact remains that a professional gets the job done, day in and day out despite the obstacles. And retires with no FAA violations and no scraped paint. And only a *few *good war stories. 
Ya done good Gus. Be justifiably proud of it.
Thank you for the thought, time & effort you made in making that post for me.
You say it much better than I ever could.
And right back at you.
You are one impressive pilot, person & teacher. A rare combination for sure.
Thank you.
Gus
This is only marginally related to the subject of the thread at hand, but I thought it was too cool not to share…
This video is from (I think) 1996; it involves a Russian cargo IL-76 taking off from an Australian airport (Canberra, I think?) in a hot, windless day.
It is really awesome in a scary way. BTW, the banter among the Australian control tower guys is definitely sarcastic at times!
Obviously, this thread is about commercial aviation. But I have a General Aviation anecdote.
Early in my training, I wasn’t quite getting the landings right. So my instructor said (well, shouted – we didn’t wear headsets then) ‘Let me show you how it’s done.’ He demonstrated the correct landing technique on a touch-and-go. As we were climbing out I asked in complete innocence, ‘Is there a reason we took off with full [40º] flaps?’ Jim didn’t say anything. He just pulled up the flaps and continued with the lesson. And it was never mentioned.
Yeah, but he/you did leap off the runway after a very short run, didn’t he?
Its also amazing how fast a big single with a constant speed prop will leap into the air with the prop in full decrease at takeoff MP at sea level. How I/we failed to hole a piston remains a mystery.
In a 150 hp Skyhawk with 40º of barn doors hanging down? The verb I’d use would be ‘struggle’, not ‘leap’. 
Serious question: How much speed does a Skyhawk lose while on the runway during a full-flap T&G? Seems to me* that even with a few seconds of roll-out before pushing the power back up to go, you’re still gonna be fairly close to flying speed.
- I’ve observed literally hundreds of T&Gs in the KC-10 as a flight deck crewmember, but only been in two GA landings - one a C150, one a C172, about 10-15 years apart. Both were FAM flights for me, and both were full-stop landings. I am, of course, aware that a 300,000lb airplane landing at 140+mph has a wee bit more inertia than a 2000lb Skyhawk landing at ~60mph.
Manual flaps or electric?