Plastic Pilot

After last landing of the day, the engineering and maintenance teams take care of the airliners. Problems reported by the pilots are examined, and various preventive checks are done. Heavier periodical maintenance is planned well in advance, but each night, planes undergo some maintenance.

A couple of years ago, a friend of mine invited me to visit a maintenance workshop while the team was doing the overnight maintenance of an AvroLiner “Jumbolino”. The plane came in at 22h30, and one of the guys taxiied it from the tarmac to the hangar.

As soon as the plane was in, the team opened the all the compartments: avionics bay, freight, APU, and even the nose, which contains the weather radar. They also used mobile stairs to get on top of the plane. If you think the Jumbolino is a small plane, that’s because you never walked on its wing…

The plane was powered by a ground generator, so the team could use all the cockpit function (see photos below). I discovered that a special sequence of keys on the Flight Management System (FMS) gives access to maintenance and diagnostics functions. Each anormal parameter is recorded and then examined at night.

Some engine maintenance was planned this night, so one of the engines had all its cowlings open. Another couple of guys were working on a flap, and had to use special tools to bend a piece in titanium. Not exaclty standard mechanics work…

All members of the team are certified mechanics, working under supervision of a team leader. All but one were airline employees. The last one was a British Aerospace hiree, expert in AvroLiner maintenance, permanently detached to this maintenance base.

Thanks a lot to this team for hosting me on this long night shift, and for the job they do each and every night to keep the airlines running safely.

I took pictures of aircraft parts that are not normally accesible to passengers. The pictures below are extracted from my “Jumbolino Maintenance” photo gallery, which contains 68 pictures.

Landing gear and gear shaft.

Avionics bay, and a very small part of the electrical circuit. The avionics bay is located in a small compartment below the cockpit, and this is where most of the electronics (radio, navigation, engine management, …) is located.

Control cables running from cockpit to the tail.

An engine with its cowling open.

The Auxilliary Power Unit (APU), an engine in the tail, producing electricity or hydraulic power while on ground.

Pedestal with power levers, dashboard and overhead panel.

Circuit breakers in the cockpit… and more in the avionics bay

The on-board kitchen

Approach routes are defined as segments - straight or arc of circles - each with a minimal altitude. The steps can be of various length and the descents have various slopes. The design of procedures is influenced by three main factors:

• Obstacles
• Airspace design - keep departures and arrivals apart
• Noise sensitive area

As long as the prescribed altitudes are respected, the management of descent is left to the crew. If your pilot think it’s fun to crash-dive, then push the throttles to stop the steep descent and finally fly low for miles, that’s his choice, but at least four categories of people won’t like it…

• Passengers won’t like the steep descent and aggressive level-off
• Airline managers will hate paying for fuel wasted to stop the descent
• Environmentalists will complain about the additional pollution
• Neighbors will be disgusted by this plane flying low over their place

The airline manager will certainly be the one with most influence on the pilot ! As good pilots will also care for the three other factors, most of them try to fly continuous descents which are economical (low power), enviroment friendly (low consumption), less noisy because of less power and airplane is always higher or at minimal altitude, and more comfortble for passengers.

If I was a marketing / management guy I would call it a win-win-win-win situation. However this is not always possible, mainly for traffic seperation purposes. The idea is to have departing aircraft (extremely noisy) climbing as quick as possible, and direct arriving traffic below departures. This sometimes force procedure designers to plan long level segments which can not be flown on low power.

With the advances of modern navigation (GPS, inertial and multi DME), planes no longer have to fly from beacon to beacon, allowing for more freedom in approach design. With so-called “Continuous Descent Approaches (CDA)”, a continuous descent is no longer an option for the pilot, they are designed so ! CDA are nothing else than long descents, some starting as high as 15′000 feet.

They can not always be flown at IDLE power because all airctafts don’t have the same performance, wind influence and traffic, but where such approaches are available they help reducing fuel consumption, noise and impact and environment.

The UK Civil Aviation Authority published this leaflet about CDAs. You can also check this page about noise on British Airways website.

This post is the fourth in a series about how modern planes are designed and operated with maximal care to the enviroment. The first one was about Jet-A1 engines, and the second about composite materials and Computer Aided Design and the thrid about electrically powered planes.

Air France is testing an in-flight system allowing passengers to use their cell-phones in flight. The initial phase is limited to text messages and data transfer, but in three months phase two will make phone calls possible.

Technically speaking the system is based on a relay located in the cabin. Because of its proximity this special relay can operate at very low power, avoiding any risk of interference. For more information about cell-phones on board, read my previous post in this topic.

As an engineer I like this system because it solves a problem and create new opportunities. However, as a passenger, I strongly DISLIKE this system, for a single reason, perfectly illustrated by french writer Jean-Paul Sartre : “L’Enfer c’est les autres”…In english: “Hell is other people”. Many passengers misbehave, invade the very small personal space available on board. This can be by widely opening newspaper, spreading papers everywhere, elbowing me, shouldering me, and many other ways.

To be fair, I certainly involuntarily invaded the personal space of some travellers sitting beside me, so I don’t really blame them, but the airlines for giving us so little room.

Allowing passengers to place phone calls on-board means that some will do, and a few will abuse of this new possibility. I can imagine the passenger beside me spending all the flight time on the phone, and being forced to listen all of the conversation, simply because there is no other possibility.

Even worse. I can imagine myself trapped between two passengers, each of them chatting loudly on their phones, possibly in different languages. If Mr. Sartre knew cell-phones he would have said “Hell is other people cell phones” !

Phones on board ? Thank you, but no, thank you !