Plane Answers: Do airliners ever intentionally takeoff without flaps?

by Kent Wien on

Welcome to Gadling’s feature, Plane Answers, where our resident airline pilot, Kent Wien, answers your questions about everything from takeoff to touchdown and beyond. Have a question of your own? Ask away!

Just a note, we’re moving Plane Answers to Mondays. The question pool has been drying up a bit lately, so let’s hear from you.

Ray asks:

I was recently on a flight from Bangkok to Singapore on an A319. As I always do (as a Private Pilot), I listen for that reassuring sound of the flaps being lowered for take off as we taxied to the runway. We got to the hold short line…nothing. My heart start beating a little faster as we crossed the first runway and still nothing…we lined up and got ready to takeoff and still NO FLAPS.

I had visions of running up to the cockpit or shouting at a stewardess and telling them. I could see myself being interviewed after we landed in a rice paddy saying “I was going to say something…!” But instead I put on my iPod and clenched my clammy fists as we screamed into the air. Is it common for a jet airliner, even with light load or short route not to use flaps for takeoff?

Hi Ray,

I can’t think of any airliners that are certified for zero flap takeoffs. But I ran your question past my resident A319/A320 expert, Chris Norton, who responded:

The most common flap setting for takeoff is flaps “1” which means leading edge and a little bit of trailing edge are extended. The trailing edge usually doesn’t travel very far, and the LE makes almost no noise.

I am not surprised that he didn’t hear the flaps, but had they tried to take off without flaps I am sure he would have heard the takeoff configuration warning up in the cockpit. The A320/319 is not approved for zero flap takeoffs.

On short runways, at heavy weights or high density altitude, we will use optimized takeoff criteria which would mean we are at balanced field length, and could use flaps 3. It is not very common though. Think Las Vegas in the summer or Orange County.

Thanks Chris, for your insight into the A319. I’ve always wondered how I’d react as a passenger if I were in the same situation as Ray–staring out the window at a wing with flaps in the up position. When riding in the back, passengers put a great deal of trust in the pilots, their checklist adherence, and the takeoff warning horn that’s installed in every airliner. The recent Spanair MD-80 accident is a rare example of the failure of all three levels of safety built into the system.

This rather scary USAToday article mentions some similar events over the past 30 years. They accurately point out that distractions and human errors happen, and if that occurs at the same time as a failure of the takeoff warning horn, the results could be disastrous.

To ensure the safety of an airliner, there are many items that are redundant. Electrical systems, hydraulics, fuel pumps and pressurization are some of the many mechanical components of an airliner that are double and triple-redundant. A single failure of any of these things isn’t disastrous, but when all the layers are compromised, accidents can happen.

There’s a certain amount of trust passengers need to have in the design of the airplane, how it’s maintained and in the pilots who fly it. If that doesn’t comfort you, just try to remember that there are 10 million flights a year, and over 10,000 flights per day in the U.S. alone.

Do you have a question about something related to the pointy end of an airplane? Ask Kent and maybe he’ll use it for next Monday’s Plane Answers feature.

Plane Answers: More takeoff and landing fears

by Kent Wien on

A number of questions came in this week relating to takeoffs and landings, and a few issues that passengers worry about. So, we’ll continue on last week’s Takeoff and Landing theme.

Eric asks this timely question:

I would like to know what purpose the wing flaps play in take off and in landing?

With the recent Spanair accident in Madrid, some reporters focused on whether or not the MD-80’s flaps and slats were extended for takeoff.

These devices, moveable panels on the back and front of the wings respectively, are used only for takeoff and landing.

A jet’s wing is designed to be at it’s most efficient while at altitude and at it’s design cruise speed. This same wing isn’t capable of flying slow enough to takeoff or land on a conventional runway.

So flaps were designed for most airplanes to increase the lift a wing can carry at these slower speeds. When the flaps are extended, the wing is essentially converted from a high-speed wing to a slow-speed wing, depending on the flap setting used.

Flaps are gradually extended based on the speed of the airplane, with the first set of flaps on an airliner usually extended when the airplane is slower than 250 knots.

For takeoff, the optimum flap setting is based mostly on the runway length. Using just the right flap setting improves efficiency and performance once the airplane is in the air. Airlines have a system for calculating that flap setting either manually in the cockpit, or through a computer print out sent via ACARS.

On the MD-80, the leading edge slats are extended and the trailing edge flaps are ‘dialed in’ to the required setting.

Taking off without any flaps extended isn’t possible for most airliners without an exceedingly long runway, maximum power set and some very careful handling by the pilot. This is why there are multiple checks prior to take off to ensure the flaps are properly set.

There’s also a loud warning horn that sounds if the throttles are advanced with the flaps not in the proper configuration for take off. Checklists, however, will likely prevent the need for the horn.

The last accident where flaps weren’t set for takeoff was a Northwest flight 255 departing from Detroit in 1987, and this might be why there has been some initial focus on the flaps as a possible cause behind last week’s Spanair crash.

It’ll be interesting to hear what happened to the Spanair flight, so we can learn from the accident. The media is rarely held accountable for the mistakes made when speculating as to a reason for an accident.

I wouldn’t hesitate to fly on an MD-80. In fact, it’s listed as the second safest airplane flying.

Dave brings up a takeoff related question:

I’m curious, if you have a severe engine problem after liftoff that you can’t recover from or go around, what is the procedure for finding a place to put down. I understand if there is a nice plowed field ahead that’s great, but what if you are in a congested area?

All airliners are required to demonstrate that they can safely operate after an engine failure at liftoff.

I suppose it’s conceivable that a dual-engine failure could happen (on a twin-engine aircraft), so in that case, the only possibility would be to land straight ahead, doing everything you can to avoid any congested areas.

Finally, Sandra asks a three-part question:

I am what I describe as a nervous flyer… I am curious to know why does the prep for landing alway feels so, well ominous?

Lights dimmed, and unless this is just my imagination…there is just something so dooming…

Some airlines require the lights to be dimmed to improve a flight attendant’s ability to see outside when on the ground. Part of their job is to assess the situation on the ground if an engine fire or other such problem were to occur and an evacuation became necessary.

Interestingly, not all airlines have that procedure.

Also, the last time I flew southwest, on final approach, the wings seemed to be dipping from left to right, right to left.

And then I flew the same airline again, and that landing was so smooth–I actually had to look out of the window to see that we were on the ground.

Ahh, yes. You’ve noticed the differences in pilot technique. Some pilots do get into what we call ‘pilot-induced oscillations,’ which are a bit annoying. You’ve had experiences with a bus driver or cab driver who wasn’t very smooth before, I’m sure. Well, you’ve just found the pilot equivalent of that driver.

What amount is attributable to the skill of the pilot, and how good a pilot is, with respect to landings??

Landings are a bit like golf. (Although I don’t play, I just had to take a swing at that analogy-no pun)

You can really feel like you have the landings perfected in a particular airplane, and then, sure enough, you can’t get a good one for weeks at a time. It’s kind of rare though to have an earth shatteringly hard landing after you’ve been flying a particular airplane for more than 6 months.

Do you have a question about something related to the pointy end of an airplane? Ask Kent and maybe he’ll use it for next Friday’s Plane Answers feature.

Plane Answers: Takeoff and landing concerns

by Kent Wien on

Welcome to Gadling’s feature, Plane Answers, where our resident airline pilot, Kent Wien, answers your questions about everything from takeoff to touchdown and beyond. Have a question of your own? Ask away!

We’ve had some great questions lately and I’m finally getting around to answering a couple of them this week. If yours hasn’t been answered, I probably have it in the que for later.

Fallyn begins:

I somehow found your site yesterday and have not gotten any work done since. I myself do not like to fly. Terrified all the way till landing. I’m sure you meet a lot of people on here that are the same way as me. I do fly though and a lot compared to most people.

I was sitting next to a nice flight attendant and he told me (because I hate take off) that autopilot takes off. This calms my nerves but now after reading [your Plane Answers feature about autopilots] I am fearful again.

To me the autopilot would know if there was a problem because computers know when there are problems but how can a human know there’s an issue with something they can not see.

Really it’s just take off that bothers me, as soon as I see the flight attendants moving around and the seat belt sign off I begin to relax. So I guess my question is how do you know it is safe to take off and that everything is in working order. I love traveling, it’s what I live for.

Oh yeah I love your blog, it’s awesome. I have read many many blogs and I have never emailed or commented on someone’s before.

Fallyn

Thanks for the nice comments, Fallyn.
There’s no airliner in the world that is currently certified for autopilot takeoffs. Part of the reason for this is because, in addition to the mechanical problems that can occur on takeoff, there are also external conditions to be aware of.

I could detail everything that could go wrong that a computer wouldn’t know about, but that might make you even more anxious about takeoffs. Let’s just say that computers wouldn’t be good at seeing a Moose on the runway.

You might be happy to learn that we practice some of the worst-case takeoff scenarios constantly in the simulator when we do our recurrent training. One of the most critical, an engine failure just as we’re lifting off, is accomplished at least five or six times during the training and check ride.

The airplane has a center screen in the middle of the cockpit called the Engine Indicating and Crew Alerting System (EICAS). Any problems that are considered important during a takeoff are illuminated here, and if the issue is significant enough, the alert is accompanied by a bell or some other tone to get the pilot’s attention.

So successfully handling an emergency during takeoff relies on a combination of the computer’s diagnostic abilities and the pilot’s judgement.

Interestingly, just 29% of all airline accidents occur on the takeoff or climb-out phase of flight.

Next time you fly, ask to visit the cockpit during boarding and take a look around. I’m sure the pilots would be happy to show you the layout of the instruments and I suspect you’ll be less anxious as you become more familiar with what’s going on upfront.

Mary asks:

We fly Southwest Airlines exclusively.

My question: why do 737’s landings become kamikaze-like missions? Why the need to come in so fast and then throw the brakes on leaving the passengers wondering if the pilot has mastered take-offs but not landings?

We recently flew into Midway, IL and used every bit of runway available. We came in typically really fast and hot, then the usual throwing on of the brakes, everyone gets pinned to their seat as the plane grumbles, pops, snaps and shakes like crazy until the plane has slowed sufficiently to avoid entering a freeway, corn field or the rear end of the 737 that landed just ahead.

This paticular landing was much harsher and everyone was aware that we used every bit of tarmac. Any chance these planes will become less violent at landing? I do feel as though we’ve landed on an aircraft carrier and gotten caught by the cables on deck.

Very observant, Mary. The 737 actually has the fastest approach speed of any of the modern Boeing airliners. Combine that with the relatively short runway length at Midway and it’s no wonder it felt like an aircraft carrier.

At the maximum landing weight, a 737-800 will touch down around 153 knots, versus 137 knots for a 757-200.

The landing gear also feels a bit stiffer on the 737, making it slightly more challenging to get a smooth touchdown versus other Boeings. Either way, a smooth landing isn’t a high priority on any runway less than 7000 feet. It’s important to land early on the runway so the weight can be placed on the wheels for more effective braking.

Reverse thrust is also used, although even with all that noise and vibration, it only shortens the rollout by a few hundred feet.

Pilots may elect to use automatic braking to slow the airplane on these shorter runways. Autobrakes have settings from 1 to 4 or 5. Maximum is usually reserved for very wet or icy runways. When used on a dry runway, these higher settings can stop the airplane in less than 3000 feet.

You’ll never have to worry about running into the airplane that lands ahead of you, since the runway needs to be clear before we’re issued a landing clearance.

So the next time you land at Midway, just think of it as an “E-Ticket” ride at Disneyland for no extra charge.

Do you have a question about something related to the pointy end of an airplane? Ask Kent and maybe he’ll use it for next Friday’s Plane Answers feature.

Plane Answers: Takeoff speeds, weights and lavatory drains

by Kent Wien on

We’re combining five questions that were recently submitted for Plane Answers. We’ll look into who foots the hotel bill for a crew’s layover, what is the typical speed and weight at takeoff, how pilots line up with a runway visually and where does that lavatory sink water go inflight?

When pilots layover for a night before returning home, who picks up the bill?

The airline picks up the tab for each crewmember’s hotel room. Meals are up to the employee, although often there’s a small per diem of about $2 an hour that’s paid by the company to cover these expenses.

I’ve always wondered what’s the ideal speed for a plane like a 737 to takeoff.

The takeoff speed is based on the weight of the airplane which varies. But you can think of it as a speed between 135 and 155 knots or so. Add 15% to convert knots to m.p.h. and you’ll have a liftoff speed of around 155 to 178 m.p.h.

What is the maximum weight that the average passenger plane (737,757 etc.) can carry and be able to takeoff and remain airborne? As a frequent flyer, I become concerned when I observe a number of 300 pound passengers boarding; and then there’s the cargo below. On occasion, I have been on a plane where the weight load was so light, passengers were asked to shift around to balance the plane weight. Does the opposite ever occur?All U.S. airlines use an average passenger weight of 190 to 195 pounds depending on the time of year. In the FAA’s mind, people in the winter either put on weight after the holidays, or they just wear more clothing. The load planning computer is able to keep the weight distribution spread out evenly through the cabin for balance purposes. The cargo is weighed before it’s loaded on to the aircraft so we know that number to the exact pound.

All of this data is totaled and sent back to the pilots who make sure that the actual weight is below the maximum allowed either structurally by the airplane’s manufacturer, or below the maximum that the runway will allow based on the airplane’s performance and the outside temperature. As an example, a 757’s maximum takeoff weight, assuming it’s not limited by a shorter runway, is 250,000 pounds. It’s empty weight, without fuel or passengers, is around 130,000 pounds.

When flying the final approach visually, how do you line up the runway centerline visually?

It’s not unlike lining up a car when turning onto a road. Controllers usually give us an intercept angle of no more than 45 degrees or so, and it’s our job to join the imaginary extended centerline from the runway. Once on final, it’s not hard to see if you’re right or left of course. Small heading corrections using the ailerons to bank left or right and we’re perfectly lined up. We also use any available navigation aids (GPS, ILS, or Localizer) to cross check our position.

This is kind of a goofy question but I always wonder about it when I use the restroom on a plane. Why is the drain stopper always closed? I notice that when I drain the water in the sink there’s an “air” sound. Does it have to do with the air pressure in the plane?

The sink drain actually ‘vents’ out of a heated drain mast (to prevent it from freezing). If they left the plunger open, it would create a lot of noise, and use a tiny amount extra bleed air to pressurize the airplane, which I imagine would cause a small decrease in fuel economy.

I took this video that shows a 777 inflight when someone is draining the sink. Take a look–It’s at the 1:14 point:


Have you ever been curious about what goes on at the pointy end of an airplane? Ask Kent and maybe he’ll use your question for next Friday’s Plane Answers feature.

Should pilots have to compete for your business?

by Kent Wien on

You’ve always dreamt of flying out to a remote lodge in the middle of nowhere in Alaska, but you’re a bit concerned about the pilots. Are they really good enough to get you into that 1000-foot strip? Wouldn’t it be nice to know just how these aviators rank?

Well, the May Day Fly-In and Airshow in Valdez, Alaska has a bush pilot competition that ranks pilots and their planes in their ability to takeoff and land in the shortest possible distances. These airplanes are highly modified to handle the tightest gravel bars Alaska has to offer. And their pilots know how to get the most out of them.

If you’re looking for some experienced pilots to take you to a great lodge, you can’t go too wrong with the Claus family. Dad, Paul, accomplished the shortest takeoff at 19 feet, and his 18-year old son Jay scored a 39-foot takeoff, which was good for 4th place in his class. The Claus family own and operate the Ultima Thule Lodge.

Here’s 18 year old Jay’s 39 foot takeoff:


I think I’m ready to go visit the Claus family and see just WHERE they’re taking this airplane!

Join Kent at Cockpit Chronicles which takes you along on each of his trips as a co-pilot on the Boeing 757 and 767 out of Boston.