Plane Answers: Trailing cones, Vegas takeoffs and crew bases

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!

Richard asks a technical question:

I have seen several photos of what I believe are later model 737s with what appears to be a small drogue chute trailing off the top back of the vertical stabilizer. I have done a few searches on the internet about it but have never found anything explaining what this item is.

I had to check with my friend Tom, who is a Boeing test pilot. He explained that this drogue chute is actually a “Trailing Cone,” which is often used in flight testing to accurately sense pressure experienced during various flight test conditions or maneuvers.

The cone stabilizes a plastic tube, which in turn conveys the sensed pressure information to the flight test instrumentation system. The pressure information must be taken at a significant distance away from the aircraft, so as to not have the pressure probe immersed in a disturbed flow field, which can occur if pressures are sensed too near the aircraft.

Usually the cone and tube are “reeled out” after takeoff, and reeled back in before landing. When being used in flight to provide accurate pressure information, the cone and tube are typically trailed behind the aircraft at distances of approximately 100 to 125 feet.

Wes asks:

My pilot on a 737 said on departure from Las Vegas that we were taking off in the opposite direction than normal. He said this was due to the following issues: it was hot and jet engines perform lower in high heat; the runway had a slight incline to it; and the plane was full. I was wondering if these were valid reasons to reverse the departure route on a runway. Thanks.
Absolutely Wes.

I don’t fly to Vegas very often, but we have “takeoff data” that lists the weight we can depart with based on each runway, the current temperature and even what the headwind or tailwind component is. In fact, each knot of tailwind will cost us between 500 and 2000 pounds of weight that we can’t carry, but we’re rarely at our maximum takeoff weight so it’s not usually a factor.

Also, as the temperature increases, the allowable takeoff weight decreases. The data also takes into account the slope of the runway.

So there are times when it’s advisable to takeoff downwind on a downward sloping runway, especially if there are no obstacles in the way after departure. These obstacles are also accounted for in the takeoff data sheet we pull up before departure through an ACARS computer, which is like a box designed to print out these computations from the company. Some airlines issue their pilots laptop computers so they can compute this takeoff data, weight and balance without the use of an ACARS.

Lee asks:

I fly often and have always wanted to ask a flight attendant or pilot how they get back home, which I know sounds dumb.

But really, the average Joe gets on a plane and thinks nothing of it, I on the other hand always wonder where you guys live and how you manage to get home. Do y’all stay at hotels a lot? Do y’all have shifts, like 7 to 3, etc.?

For instance, I fly (Jet Blue) to San Diego quite often. The pilot always tells us they’re based out of Long Beach, CA. Well, does that mean they fly an empty plane from Long Beach to San Diego and vise-versa when they get through?

I have to assume a typical airline pilot doesn’t have a 40-hour week.

The large airlines may have from four to nine different crew bases where pilots and flight attendants generally start and end their trips from. Some crew members prefer to live somewhere else and commute into their base to start their trip. In these cases, they don’t get paid for traveling to and from work, obviously.

Occasionally we’ll be called out to fly a trip from another city, so the company will ‘deadhead’ us to pick up that flight which usually ends up at our base. Ironically, as I write this, we’re deadheading down to San Juan to pick up a flight back to Boston.

We’re paid for 50 to 100% of the flight time while deadheading depending on which airline a pilot or flight attendant works for.

Most crews live within a few hours of their base, which is typically located at a major city such as New York, Los Angeles, Chicago, Atlanta, Miami, San Francisco or in my case, Boston.

Occasionally a base such as New York will be made up of two or three airports that crews may have to work from.

When we’re at work on a multi-day trip, each pilot and flight attendant stays in hotels provided by the airline.

While they’re aren’t really any scheduled ‘shifts’ we’re able to bid for the following month’s schedule (see my Cockpit Chronicles on Bidding) we can choose between different destinations, departure times and the number of days away in a row.

Most trips are between one and four days at my company.

In your JetBlue example, since the crew is based in Long Beach, I suspect they’re actually laying over in San Diego. They will likely fly somewhere else the next day before flying back home to Long Beach.

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.