Cockpit Chronicles: Eight ways to slow a jet

One of my first posts on Cockpit Chronicles was an explanation on how to park a 757. At the risk of catering only to people who have recently acquired their own Boeing jets, I’d like to continue with another lesson.

The eight ways to slow a jet

When you’re driving your 5-speed manual transmission car and you exit an offramp, besides just taking your foot off the gas pedal, there are a couple of different ways that you can slow down. Most people probably put on the brakes, but you could also downshift as well.

In an airliner, there are four different ways inflight and four methods on the ground to slow a jet, and often these techniques can be used in conjunction.

Unlike turboprop airplanes, jets are rather difficult to slow down and require a bit of planning in advance to avoid burning too much fuel or ending up too high at the airport for landing.

So let’s start with our Boeing that’s at 33,000 feet. Pilots will use a rough “3 to 1” guide when deciding when they’ll need to start down, adjusting for wind as needed.

To do that, take the 33,000 feet, drop the zeros and multiply it by three. 33 X 3 = 99 miles.

So, for a descent at idle thrust, the pilots will need to start down within 99 miles of the airport. Any later and they’ll be too high and need to add drag to get down, and any sooner and they may need to add power and level off for a while. Either way, more fuel is burned.

A side note: If the engines were to fail, our airplane would likely be able to make it to the runway if it were within that 99 mile point. It’s just going to take some perfect planning on the part of the pilots, as was the case with the Air Transat and Air Canada flights.

Since an airplane burns far less fuel at altitude, it’s best to stay up high until the airplane can descend, ideally at idle thrust, all the way to the final approach segment. That’s our goal, subject to air traffic control requiring something different.

It’s not uncommon, especially in the U.S., for air traffic controllers to leave you at altitude past your normal beginning of descent point. In this case, it’s going to take more than idle thrust to descend quickly enough.Speed Brakes

In this situation, we can use speed brakes, which are the panels on top of the wing that move up equally on both wings to increase the drag on an airplane and reduce the lift.

So they’re the best method to initially increase the rate of descent and/or slow the airplane.

Since there are usually no airspeed limitations when using speed brakes, they can be deployed anytime they’re needed.


The next method to slow an airplane involves using the flaps. These devices are panels that extend from the leading and trailing edges of the jet to change the shape of the wing to provide more lift. This allows a high-speed wing to quickly transform into a wing that can keep the jet in the air at much lower speeds.

In addition to creating more lift, flaps also create drag, and can slow a jet nicely. Unfortunately, we can’t begin to use the flaps until below 250 knots or so. Each step of the flaps has a different speed limit, above which too much stress will be placed on the flaps and a maintenance inspection would be necessary if that limit were exceeded.

We now have a program called FOQA, or Flight Operations Quality Assurance, that records the exact speed at which the flaps are deployed among many other parameters and sends a report to the company (see my personal experiences with FOQA here). Should the flap speed limits be exceeded, the airplane is taken out of service and given a thorough inspection, sometimes costing tens of thousands of dollars in maintenance man-hours to accomplish, not to mention the revenue lost when an airplane isn’t flying.

So let’s say that we’re flying into Miami or Los Angeles which are two airports known for the ‘slam dunking’ that ATC occasionally needs on certain arrivals.

Imagine that you’re now at 230 knots with the first notch of flaps extended and you still aren’t descending at a high enough rate. What can you do? More flaps would add drag, but you’ll need to be below 220 knots before you can go to flaps 5. And you’d better not hit a gust or any turbulence that sends you above 220 with those flaps out.

Landing Gear

So the next solution is the landing gear. This can be extended at any time you’re showing 270 knots or less of airspeed. They add a similar amount of drag as the spoilers, which are still extended in our scenario.

Pull up, pull up!

Finally, as with any airplane, our 4th method to decelerate is pretty basic; lift the nose up which initially decreases our rate of descent. We adjust the descent to slow the aircraft to bring the flaps out on schedule.

Often times there are points along an arrival where we’ll need to be at a certain speed and altitude. These ‘crossing restrictions’ are very important to meet and add another challenge for the arrival.

Pull Up, Pull Up!

Fortunately we don’t have to rely only on the 3 to 1 calculation to properly meet these targets when planning our descent. We can plug in the speed and altitude we want when flying over a waypoint into the FMS, or Flight Management System, that will calculate the time we should start down, using a function called VNAV, or Vertical Navigation.

Slowing down after landing – Ground Spoilers

Finally when we touch down, ground spoilers will automatically deploy from the top of the wings. This is done by using the same handle which deploy the same panels as the speed brakes, but now a few extra panels that open even further than the speed brakes are included.

These panels not only give us added drag, but when deployed, they add weight to the wheels which dramatically increases the effectiveness of our second method of stopping, the brakes.


All airliner brakes have anti-skid protection and the option to use ‘autobrakes’ for landing. We can preset the brakes before landing to automatically activate soon after we touch down. There are five different levels to choose from, with ‘max auto’ the one to use on slick runways. The same setting on a dry runway would leave a nose print in the setback in front of you, however.

To manually operate the brakes, pressure is applied to the top of the rudder pedals with your toes which, if they were selected, will also kick off the autobrakes. We generally don’t manually apply brakes until we’re below 100 knots. Pilots can even control the right and left brakes independently by pressing the tops of the right or left rudder pedals.

Reverse thrust

The noisiest, and third most effective way to stop an airplane on the ground is to use reverse thrust. This is done by lifting some handles that are in front of the thrust levers (throttles) when they’re at idle. The farther we pull these handles, the more thrust is deflected forwards to slow the jet. If these devices are inoperative, or a specific airport has restrictions on their use during late night hours, only 400 to 600 extra feet are needed for landing.

As we slow through 80 knots, we’ll bring the reverse thrust to idle and coming through 60 knots we are advised to stow the reverse thrust sleeve completely.

Here is a video of the reversers in operation that I caught while mechanics were making adjustments.

All of these methods can be seen in this picture of the center console of a Boeing 757:

Aerodynamic braking

There’s actually a fourth method of slowing an airplane after landing, but it’s generally not effective in the airline world, and more often seen when watching the Space Shuttle land. Aerodynamic braking is when the nose wheel is held high off the ground to use the drag of the airplane as a way to slow down. It’s not really effective, and it delays our ability to use brakes (and reverse thrust on the MD-80) while the nose wheel is still off the ground.

To taxi to the gate, the captain will use a combination of throttle and brakes to control the speed, which the FAA says shouldn’t exceed that of a person walking briskly. In reality, five to fifteen knots while taxiing is far more common.

So there you go. Oh, and congratulations on your recent jet acquisition. Or for those of you just worried about an Airport ’75 event occurring on your next flight, this could come in handy.

Either way, stay tuned for some more obscure airline flying tips!

Cockpit Chronicles takes you along on some of Kent’s trips as an international co-pilot on the Boeing 757 and 767 based in New York. Have any questions for Kent? Talk to him on the Cockpit Chronicles Facebook page or follow Kent on Twitter @veryjr.

Plane Answers: Kent’s 3 favorite and 3 most dreaded runways.

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!

Deb asks:

Are there any favorite/hated runways by pilots? Pictures and videos of the one in St. Maarten made me wonder.

I’m sure every pilot has a few favorite or hated runways, and I’m no exception. Here are my top and bottom three:

My three favorite:

LGA – New York’s LaGuardia

With its reputation for delays and cancellations, LGA might not be on the top of most passengers’ lists. But it’s often the challenging runways that are the most enjoyable for pilots. While LaGuardia‘s runway 13/31 is short at just 7,003 feet, and it has water on both ends of the runway, the expressway visual takes you over the former Shea stadium and it requires some planning to make the sharp turn and perfectly line up on runway 31. But the most beautiful approach I’ve ever flown is the ‘River Visual’ up the Hudson to runway 13. Sailing past Manhattan at night, with the buildings seemingly at eye level, and then making a right turn over Central Park to line up with the runway, is certainly a rush.

SXM – St. Maarten

You mention St. Maarten, and I’d actually have to list it as one of my favorites. Coincidently, it’s also 7,003 feet long. But the fun part about St. Maarten are the spectators that gather at the end of the runway to witness the landing airplanes fly over at less than 50 feet above the ground. It’s probably the closest spectators can get to a landing aircraft without being on board. And who knows, maybe someone like Matt Hintsa will snap a picture like this of your landing:

SAN – San Diego

Finally, I must admit to a fondness for yet another short runway. San Diego‘s Lindbergh field offers a scenic arrival, and the approach crosses rather close to a parking garage located near the field. Since there’s no ILS, you have to be right on the glidepath during the approach. If you’re precise, the radar altimeter in the cockpit will read 190 feet as you pass over the garage, making for the perfect approach to runway 27.

Three worst:

NME – Nightmute, Alaska

Ahh, Nightmute. At 1,600 feet long, you’re probably not going to find anything larger than a Twin Otter flying there. Most of the landings I remember in Nightmute were in a strong crosswind during the winter on a packed, snow-covered runway that resembled a frozen lake. Reading the airport notes from this place might give you a better picture.


I’m sure glad those days are behind me.

CCS – Caracas, Venezuela

Runway 10 at Caracas, Venezuela. It curves down, dropping 88 feet from the beginning of the runway to the end. Even if you do get a smooth touchdown, the runway is so rough that no one would realize it.

MIA – Miami, Florida

And finally, there’s Miami‘s runway 30. Nothing challenging here, it’s long, it’s wide, it’s even smooth. But I never seem to get a nice landing there. So I’m adding it to the list. Take that, runway 3-0!

I’d be curious to hear other pilots’ favorite and least favorite runways. Leave a comment and let us know!

Roger asks:

My friends & I live near an approaching flight path, and regularly get into discussions about planes and their landing or approach speeds. Do larger jets have a slower approach speed, or does it just appear that way? Do smaller ones have a higher approach speed, or does it just seem that way, or are they all flying at the same speed?

An answer to this will sort out several arguments.

I think I can help you win the argument either way.

Below are some final approach speeds for various airliners. I figured them based on the maximum landing weight for each aircraft type using the ‘normal’ flap setting, which may not be the maximum flaps.

From fastest to slowest:

747-400: 157 (174 m.p.h.)
737-800: 148 (170 m.p.h.)
767-300: 142 (163 m.p.h.)
A320: 142 (163 m.p.h)
EMB-145: 139 (160 m.p.h.)
777-200: 138 (159 m.p.h.)
MD-80: 136 (156 m.p.h.)
A300: 135 (155 m.p.h.)
A319: 132 (152 m.p.h.)
757: 132 (152 m.p.h.)

On a calm day, we’ll add five knots to the speeds above. If it’s gusty, we can add up to 20 knots to the approach speed.

Interestingly, while the 747 is the fastest, it definitely looks like the slowest on approach due to its size. At 232 feet long, it’s over 100 feet longer than the stretched 737-800.

While studying auto accidents involving railroad crossings, the NTSB attributed the problems to the Leibowitz hypothesis, which states that the speed of larger objects, like trains, is underestimated by observers owing to a normal deficiency of visual processing.

But if that doesn’t help you win your argument, you could use this counter example:

Take the EMB-145, a 50-seat regional jet, and compare it to the surprisingly slow speed of the 757. In this example, the RJ actually does fly faster on approach, and since it’s much smaller than the 757, it really looks like it’s late for a date.

So I think you’re covered either way. Good luck!

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.

Plane Answers: Takeoff speeds, weights and lavatory drains

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.