Regardless of the distance traveled or the time spent aloft, all airplanes must eventually return to earth. For passengers, the descent leg means the flight is almost over. For the crew, the descent phase involves communication, coordination, planning, and even math. Let’s examine some of the highlights your pilots deal with after leaving cruise altitude.
In Selecting the Best Cruise Altitude, we discussed how fuel consumption decreases as altitude increases. For airlines, reducing fuel consumption whenever it’s safely possible is a major goal. As it happens, the descent phase is the most fuel-efficient airborne leg. To maximize fuel savings, the aviation industry has developed procedures for what’s called economy descent. Economy descent, or econ descent, is the practice by which airplanes descend at idle power. At idle, the engines consume the least possible amount of fuel, which the airlines love. The goals of econ descent are to: 1. Remain at the fuel-efficient cruise altitude as long as possible 2. Descend at idle power for the entire descent (if possible). Ideally, the descent leg would be one continuous glide down from cruise altitude to the runway. Due to air traffic constraints, this is rarely feasible. However, industry authorities continue to evaluate possible procedural updates to accommodate econ descent improvements.
As you know, airports are noisy places. Airplanes create an incredible amount of noise, which is a significant source for complaints from airport neighbors. In many areas, noise abatement procedures have been established to enforce against unwanted sound. To avoid unnecessary disruption, pilots try to minimize the noise impact of their aircraft. The major techniques to reduce engine noise are to: 1. Gain/maintain extra altitude after takeoff/before landing 2. Reduce engine power settings/rpm. 3. Alter course to avoid populated/noise sensitive areas. As you can see, econ descent procedures incorporate noise abatement tactics. In addition, some approach courses and arrival routes are tailored to avoid noise sensitive areas.
Coordination with Support Teams
Another important pilot task prior to arrival is to report in range. The “In Range” notification, which can be completed via radio or electronic message (or a combination), notifies gate personnel and company ops of assistance the arriving flight will need at the gate. The in range call relays fuel status, unique passenger needs (wheelchair, interpreter, etc.), maintenance/equipment needs, and any other relevant information. This call is often made 10-20 minutes before the estimated arrival time, which allows supporting staff to line up necessary personnel, equipment, and/or fuel. At times, when the plane will be departing soon after arrival, the crew can arrange for a “quick turn” procedure to speed up the requisite gate tasks.
Approach & Landing Prep
Professional flight crews also use descent time to prepare for the approach & landing phases. These flight stages are often high-workload situations that require advance planning to ensure safety requirements are met. During the approach briefing, the crew will set up navigation equipment, tune radios, and analyze the characteristics of the destination airport. They also review the expected instrument approach procedure and calculate approach & landing speeds. By preparing ahead of time, the pilots are then able to concentrate once entering the terminal environment.
Traffic and Clearance
The closer to the airport the plane gets, the more congested the airspace becomes. Flight crews maintain extra vigilance near the airport, which involves watching for potential traffic conflicts and visually locating planes they’re to follow to the runway (“sequence behind”). During this phase, you’ve probably heard your pilots advise “flight attendants prepare for landing” over the cabin speakers. An important final step is to receive clearance to land. While this might seem obvious, it can be easy to overlook amid the activities in the cockpit and the traffic out the window. Each aircraft must receive a landing clearance for the appropriate runway before touching down. Failure to receive clearance can potentially compromise safety. For ALL tasks required during descent, crewmembers refer to the appropriate checklists and company procedures. In the future, we’ll cover some of the specifics for configuring the plane for landing. Until then, please fasten your seatbelts and stow your tray tables.