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!

Paul asks:

Hi Kent,

My question is about winglets. We see most of the RJ's have winglets and many airlines are either retrofitting or purchasing their 757's and 737's to include winglets.

If these are such a performance enhancer and fuel saver, why don't we see winglets on 767 and 777 aircraft? There are many of these aircraft in the air today so one might assume an opportunity for fuel reduction and cost savings is being lost. What's your take on this?

That's a very good point, Paul. I asked about the 777 a few years ago and I've been told that the wing design on the large Boeing won't accept winglets. I'm not sure if it couldn't handle them structurally or if the wing was already efficient enough that winglets wouldn't help.

I do know that the wingspan of a 777 was a significant concern for airlines when they were planning the gate spacing before the airplane was delivered. Since the 757 with winglets has a 10 foot longer span, I would think it might be a problem with our infrastructure at certain airports.

American announced last year that they'd be retrofitting each of their 767's to include winglets. We should see the first one modified by next year. Here are a few pictures of the first airplanes being converted.

Why didn't they retrofit these airplanes sooner? Back in 2000, the 737 winglet conversion was just under $1 million dollars. With the recent jump in fuel prices, I'm sure the kits are a bit more expensive, but the 4% fuel savings would easily offset the conversion price.

Hi Kent -

Can you explain the flight director and how it is used by pilots?

Thanks, Ryan.

Sure, Ryan.

A flight director gives us information on the pitch or roll attitude needed during a particular phase of flight. It's part of the autopilot system.

You can think of it as an indicator (made up of either "V" bars or crosshairs depending on the airplane) that shows the autopilot or even a pilot who happens to be hand-flying the airplane which way to turn and how much bank or climb is needed to turn, climb, speed up or slow down the airplane.

It's kind of like having a person beside you saying, "OK, pitch it up to three degrees and bank 25 degrees and roll out on a 090 degree heading." In level flight the flight director will show you the attitude required to hold an altitude.

Some pilots prefer to turn the flight director off and fly the airplane in a raw data mode, which means that they'll decide when, where and how much they'll pitch and roll.

Here's a picture of the common "V" bar flight director displaying a turn:



And here's the attitude indicator with the flight director off:




Hi Kent,

I had a question regarding oceanic travel. I am of the understanding that pretty much all traffic between North American and Europe goes through the North Atlantic Tracks using HF radio for positioning reports (or ACARS). How do aircraft going from North America to Africa, or S America to Europe cross the pond? Are there separate tracks/ oceanic FIRs for those specific routes? There are similar tracks for trans-pacific routings to Japan and Australia too correct?

Matt

Matt is talking about the five parallel routes that go across the Atlantic. These routes change twice a day to take advantage of favorable winds–once for the westbound morning/afternoon arrivals and again for the eastbound evening/night flights.

This track system is unique to the North Atlantic. If your flight happens to be going from New York to South Africa, there's a chance you won't be on the track system at all, but you will be flying what's called a random route.

If this random route happens to cross one of the tracks, the airplane will be restricted from flying above FL 290 (Flight Level 290, or 29,000 feet essentially).

In the Pacific, there are tracks, but they don't change on a daily basis and they're made up of named waypoints instead of the coordinates that define the North Atlantic tracks.



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.

Filed under: Plane Answers