iFly Blog

 

Thus far, most of our posts have looked at the steps leading up to takeoff. Today we’ll examine what happens once the plane departs terra firma. While the takeoff and climb legs might appear simple and self-explanatory, both involve important steps that greatly contribute to the safety of each flight.

V1:  A Critical Airspeed

Although we previously reviewed the need to calculate speeds & power settings (see The Paperwork Pile of a Puddle Jumper Pilot), one speed in particular deserves special attention. V1 is defined as “the critical engine failure recognition speed or takeoff decision speed.” Whenever you fly, it’s a sure bet your pilots are discussing V1 while they taxi towards the runway. Attaining V1 is a top priority during takeoff. Any abnormal developments below this speed mean the crew will abort the takeoff. At or above V1 the issue will be handled in the air, whether or not the plane has actually become airborne yet. Due to a variety of factors, it’s actually safer to continue the takeoff run (once at or above V1) than to try to stop the aircraft. Pilots are keenly aware of this, and thus place special emphasis on monitoring airspeed during takeoff.

Alternates and Contingency Plans

Another discussion pilots have before takeoff involves alternate plans of action. These plans address issues that arise immediately after takeoff, while enroute, upon approach to the destination airport, and any other situation that might require an alternate airport/landing site. In some instances, mainly due to low ceilings/visibility or geographical restrictions (i.e. high terrain), airplanes are unable to return to their departure airport following takeoff. In these instances, pilots & dispatchers choose a departure alternate, a (relatively) nearby airport the plane can divert to following an abnormal occurrence. In extreme instances, the crew might have to choose an off-airport landing site. Remember Capt. Chesley Sullenberger and US Airways Flight 1549? While the outcome was indeed miraculous following the flight’s double engine failure, the happy ending was largely due to the contingencies developed by Capt. Sullenberger and his crew.

Noteworthy Climb Altitudes

Throughout the climb to cruise altitude, pilots monitor a few key altitudes. These altitudes serve as milestones the crew uses to perform essential tasks.

400 ft:  After liftoff, the crew’s immediate priority is to reach an altitude of 400 feet. This altitude is widely used to transition from max performance climb to cruise climb. Why 400? This number is used because, by 400 ft, the plane will have climbed above most nearby obstacles. With a little altitude between the plane and the surface, the crew transitions to a cruise climb, at which a higher airspeed and slightly shallower climb angle are adopted. Any flaps used during takeoff will be retracted once reaching 400’ and accessory items (like pressurization), which slightly decrease engine power output, are activated.

10,000 ft: Think your pilots are discussing last night’s ballgame during climb? Absolutely not. Below 10,000 ft, sterile cockpit rules apply, meaning only essential communication is permitted. At lower altitudes, the crew is busy performing after-takeoff & climb checklists, communicating with air traffic control (ATC), monitoring instruments, and configuring the airplane. Additionally, airspace below 10,000’ frequently contains a large amount of air traffic, particularly near airports. Above 10,000; things tend to settle down and traffic usually thins a bit. At this point, idle chatter is permitted and items like landing lights (used to increase the plane’s visibility) are turned off.

18,000 ft: This altitude marks the lower limit of Class A airspace. Class A is off-limits to visual traffic and is the realm of airliners and business jets. At 18,000 ft, all aircraft set their altimeters to 29.92 in. Hg (atmospheric pressure), which allows for a uniform standard for high-altitude operations. Below 18,000 ft, aircraft utilize local airports’ pressure readings.

Throughout takeoff and climb, pilots are busy planning, monitoring, anticipating, and adapting to both expected and unexpected occurrences. This thorough dedication to safety has made airline travel the safest transportation system in the world. The next time you fly, rest assured your crew is prepared for and capable of handling nearly any possible situation.

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