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.

Flaps

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.

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.

Free Montreal travel in three simple steps

Do you like Montreal? I have to admit, I’ve been there three times in the past two years, and I just can’t get enough of it. The minute I hit the streets of Old Montreal, I find myself craving a hotdog at the St-Denis Pool Hall before dashing over to the art galleries on St-Paul Ouest. Even with winter approaching rapidly, I’m feeling the pull up north.

So, I was pretty excited by a cool contest that just hit the web from CheapOair, and the social media junkie in me was drawn in. The upside is pretty exciting: two roundtrip tickets to Montreal from Air Canada, two luxurious nights at the Montreal Marriott Chateau and tickets to a variety of local attractions around the city from Tourism Montreal.

If you win, I strongly suggest you go hang out with local foodie Katerine Rollet for a while. Ask her about the local hotdogs, and she’ll probably know I put you up to it.

So, how do score this getaway? Well, you have to click around to three sites … and maybe do a little typing. There are three simple steps:

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1. Head over to Facebook – assuming you’re already one of the 500 million users of the site. “Like” the Montreal Buzz page.

2. While you’re in Facebook, click over to CheapOair’s page and “like” that, too.

3. Finally, you’ll have to leave Facebook (don’t worry, you can – and probably will – wind up back there at some point during the day). Visit the Tourism Montreal blog and leave a comment telling everyone why you want to head up there. You won’t get extra points for mentioning the hotdogs in town, but I haven’t heard that doing so will hurt.

The contest kicks off November 1, 2010 and ends on November 5, 2010. The winner will be announced on November 8, 2010. Fortunately, you won’t have to wait long to see if you’ll get to hit the road.

Click here to see what else there is to do in Montreal!

Veils and YouTube trigger Canadian security investigation over passenger identification


Score one for social media: some guy popped a video of two fully veiled women boarding a plane on YouTube, and now the Canadian authorities are investigating. The video is said to show passengers hopping onto an Air Canada flight to London from Montreal on July 11, 2010. The beef isn’t so much the veils as ensuring “that airline personnel are verifying the identity of all of passengers before they board a flight,” according to the AFP.

In the video, shot by a British traveler, the women were not required to show their faces before boarding, which Canadian Minister of Transportation John Baird called “deeply disturbing” in a statement released Sunday. He added that it “poses a serious threat to the security of the air travelling public.”

Air Canada passenger falls asleep on plane – wakes up in maintenance hangar

We’ve probably all been there – you get on your flight, feeling so tired that you pass out before the plane takes off.

But in most cases, you’ll be awake right after you miss the drinks service. Air Canada passenger Kris Lines must have had the nap of his life, because he passed out right after taking off, and was awoken by a maintenance engineer inside a hangar at Vancouver airport.

Apparently none of the Air Canada flight crew members took the time to check whether they had left anyone on board, and simply got off the plane leaving Mr. Lines fast asleep.

When he complained to the airline, they offered him a “generous” 20% off voucher for a future flight. Mr. Lines is not satisfied with that offer, and calls it “absolute craziness”. I’m not entirely sure what else the airline could do for him, other than making sure their staff are retrained to check the plane for sleeping passengers. Still, if this happened to me, I too would probably fight for a little more than a useless discount voucher.

So, next time you feel like you are going to fall asleep on your flight, you may want to ask a seatmate to nudge you awake upon landing. Mr. Lines was lucky that the plane was moved to a hangar, at the end of the day, many planes are just parked for the night.

Canadian airline forced to remove smelly passenger from plane

We’ve already been told that being too fat will have you kicked off the plane, but now “too smelly” is apparently also a (very) good reason to be sent back into the terminal.

Not much is known about the specifics, but several weeks ago, Canadian airline Jazz had to remove a passenger because of his “brutal” stench.

I’ve been in the unlucky situation of sitting next to a stinker, and it really is a horrible position to be in – especially when you are dealing with the kind of stench that can’t be masked by a spritz of Old Spice.

Thankfully, someone at Jazz had the guts to tell the passenger that he had to get off the plane. In situations like this, I’d rather see them embarrass one passenger, than inconvenience an entire plane.

The airline wouldn’t reveal any specifics, citing privacy concerns, but they do admit that a passenger was removed, mentioning “safety concerns”.

As far as I’m concerned, that is a perfect way to handle it. Seriously, I can understand smelling a little nasty after a few days on the road, but I’ve encountered people I could smell 4 rows up. Do everyone a favor, and take a shower before you fly!

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(Image from: Getty)