As much as the cockpit looks like a car with that familiar steering wheel, the yoke isn’t actually how the pilot steers on the ground. Controlling an aircraft is no easy task, and movement on the ground is no exception.
If the control column isn’t what’s deciding whether you go left or right, then what is?
It depends on whether the aircraft needs to steer on a taxiway, during take-off and landing, or while being pushed back. While in the first two cases, the steering is handled using a tiller which steers the nose gear, aircraft rolling down the runway at high speeds steer using their rudder. Aircraft being pushed back are turned in the right direction by the towing tug operator.
How Do Aircraft Steer on Taxiways?
Most transport category aircraft actually use a tiller in order to steer on the ground, while moving in between taxiways on their way to the runway. The tiller is often found on the Captain’s side, although once in a while you’ll have a situation where there might be one on the copilot’s side as well.
The tiller allows the Captain to steer left and right, much like a steering wheel, but instead looks like a small handle that is placed slightly out of the way to the side. Since the tiller is often used with one hand and takes a bit of practice to get used to, a pilot will first use one in a full-motion simulator to get the feel of it beforehand.
Unsteady movements on the tiller can result in passengers getting tossed around, so practice makes perfect.
It isn’t recommended to be taxiing at a fast pace because you can easily lose control. The faster you taxi, the more sensitive the tiller is and the easier it is to move like a snake along a taxiway.
Speed is controlled by the power output decided by the pilot, who does so by adjusting the power levers. The more power you add, the faster you move, however, there might be a slight delay so it’s best practice not to add too much power too quickly.
A pilot can taxi down a straight taxiway up to 20kts, which is around 23mph. During low visibility operations, pilots tend to taxi a little slower in order to stop more easily, improving braking.
The braking system found in larger aircraft often come with additional enhancements to prevent loss of control at high speeds, and an anti-skid system is often one of the most used. The anti-skid system prevents an aircraft from skidding. It automatically releases the brake on the main wheel that isn’t moving fast enough compared to the speed of the aircraft.
In the early days, there were no backup brake systems, but of course, that has changed. Most passenger aircraft have a form of brake redundancy by having multiple hydraulic systems, as well as a set of procedures to ensure no loss in braking efficiency.
How Do aircraft Steer During Pushback?
So how do aircraft move back from the gate? Pushback always starts with a clearance, since the pilot can’t see behind them and they need permission before starting their departure. The pilot will request a clearance, and once the customer service representatives and the ramp attendants confirm that all their tasks are done, the door is closed.
Once a pushback clearance is given from ATC, it’s time to start moving. The ramp attendants will receive permission from the pilot and will begin to hook up a vehicle to the front of the aircraft, known as a tug.
The tug is a powerful vehicle that can look like a large golf cart, and is driven by a ramp attendant. The rampee hooks up the tug to the nosewheel of the aircraft with a tow bar. The tow bar can pivot, and a skilled ramp attendant will easily begin to push back the aircraft while making smooth turns, placing the aircraft in the correct position.
The most important part of pushback, and in pretty much every aspect of aviation, is communication. The ramp attendant and the pilot need to be able to talk to each other, so the aircraft can arrive in the right position.
Since most locations don’t use a headset that connects to the exterior of the aircraft for communication, marshalling is used instead. Marshalling is a standard set of hand signals used throughout the world to allow pilots and ramp attendants to communicate.
The pilot will indicate to the ramp attendant that they are ready to move by signaling brake release, clear for pushback, and sometimes the direction they want the nose to face.
How Do Aircraft Steer on a Runway?
Aircraft need a clearance before entering the runway and will wait for permission while holding short. Once given the go-ahead by ATC, the pilot will add power and use the tiller to line up along the center of the runway.
The nose wheel will be centered by the pilot to allow a smooth transition. Once given the go-ahead for takeoff, the pilot flying will confirm their control of the aircraft, and start to steadily increase power to the take-off setting.
The pilot will maintain runway centerline with the tiller, and as the aircraft accelerates the tiller will become increasingly more sensitive. As the tiller becomes less reliable to maintain directional control the pilot will switch to the rudder pedals.
Since nose wheel steering is connected to the rudder pedals, which are also used to control yaw, the aircraft can be steadily maintained on the centerline during takeoff with positive controls from the pilot.
Once the aircraft rotates and is airborne, the pilot will continue to use the rudder pedals to control the yaw and have a smooth transition into the air.
When landing pilots maintain directional control on the runway using the rudder pedals until the aircraft’s speed begins to decrease.
Once the aircraft slows to around 60 knots or less, the pilot flying will often relinquish control to the Captain who will resume steering with the tiller. Some company Standard Operating Procedures (SOPs) prefer the aircraft to come to a complete stop on the runway before transferring control.
Once the aircraft has landed safely and taxiid to the gate, the pilots will shutdown the aircraft and unload the passengers. It will be time to either go home, or load the next group for a quick turn and departure.
Although not as much time is spent on the ground as in the air, steering on the ground is just as important a job for the pilots as flying the aircraft.
In fact, because there are more obstacles on the ground, some pilots will argue that taxiing is more nerve-wracking compared to flying itself.