Airline flight planning

Believe it or not, there really was a time when airline pilots would use an E6-B flight computer, aka the Whiz Wheel, to compute their airspeed, times, and fuel burn (in his book, North Star Over My Shoulder, Robert Buck waxes philosophic about the challenges of completing his calculations in a timely manner on the ground, and during ‘dark and stormy nights’ aloft). They would also take the time to pore over hand-drawn weather charts, and they had an intimate knowledge of the terrain along their route system, not because they wanted to, but because they had to.

Back in the day, so to speak, pilots were much more involved in the planning of their flights. Radio communication with the company HQ was rare to non-existent after takeoff. Instead, communication took place between the flight and various stations along the route, as well as with other flights. Further, there was no onboard weather radar, let alone ground-based radar systems like we have today.

In the modern age, pilots have very little to do with planning their flights. The primary aid in that task is the dispatcher. The dispatcher is actually the individual responsible for putting together the paperwork and filing the flight plan. Nearly every scheduled flight follows a “canned” route–one that is stored in the airplane’s flight management system. If there is no FMS, the common route is used. Such routes are coordinated between the airline and the various ATC facilities, so most airlines flying between two cities use the same route. The dispatcher then takes into account current and forecast weather, the projected payload of passengers and cargo, and determines the appropriate amount of fuel to load; sometimes extra fuel is loaded when there is a substantial difference in the price of fuel between two airports, of if the load will be light enough to round-trip the fuel.

Dispatchers also have the ability to tap into the real time data-bases for NOTAMS, TFR’s, etc. while planning the flight. PIREPs also play a critical role in the flight planning process, especially with regards to reports of turbulence, which is the most common cause of in-flight injuries to passengers and flight attendants.  They also have to take into account any broken items on the airplane that may affect performance. For instance, on the CRJ and some other jets, the loss of an air conditioning pack limits the airplane to 25,000 feet, and on all jets, damage to the RVSM critical area limits altitudes to 28,000 feet or less. Other deferred items can limit the indicated airspeed to 250 knots or less, which, in a jet, is painfully slow.

Once the crew shows up for work or lands from a previous flight, they can review the plan the dispatcher has assembled via the dispatch release, which is the long string of paper that you usually see printing behind the gate agents in the airport. The release has the same basic information as a regular flight plan, plus weather, NOTAMS, PIREPS, and station information specific to the flight. If the crew wants to discuss something or make a change based on their own interpretation of the weather or perhaps from talking to other crews that have been flying, they can call the dispatcher and discuss it. It is important to keep in mind that, while the captain has full authority of the airplane in flight, in Part 121 operations, the dispatcher is equally responsible for the flight, and most importantly, must agree to any material changes, and has the authority to prevent a takeoff if he disagrees with the captain. It is a weighty responsibility, and it is one reason why dispatchers, like pilots, must be certificated by the FAA. Any pilot who tries to takeoff without a dispatchers’ concurrence may well have taken off for the last time.

Once the plane is airborne, the dispatcher can keep tabs on the flight on a computer (similar to Flightaware), and also has the ability to contact the crew if there is a significant change that must be communicated to the crew, such as deteriorating weather, a change in the alternate, or even a preemptive diversion.

While pilots are not as intimately involved in flight planning as they used to be—we knew more about the route of our first solo cross-country than we do about most of our airline flights—it is reassuring to know the job is being professionally done by someone who is not only competent, but who has some skin in the game as well.

–Chip Wright

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