For a plane to take off from an aircraft carrier, it must acquire enough lift force to take off from the short flight deck. Some of this lift force is produced by the wind, but most comes from on-board machinery. To generate lift, planes are launched by four catapults on the ship’s flight deck. The catapults are powered by pistons that are housed inside cylinders. Where Russia, India and China use Ski-jump ramp, aircraft that have a high thrust-to-weight ratio such as Su-33 or MiG-29K and thus limits the kind of aircraft that can be operated from the carrier.
Compared to CATOBAR (Catapult Assisted Take-Off But Arrested Recovery), STOBAR (Short Take-Off But Arrested Recovery) is less expensive to develop. It is easier to operate than a CATOBAR configuration which requires large number of operators to launch the aircraft. Lack of any moving parts in ski-jump makes it less expensive to maintain the launch system.It does not require any additional system to generate force required to launch the aircraft unlike CATOBAR where an external force is needed to be generated either from steam catapult or Electromagnetic Aircraft Launch System (EMALS) to launch the aircraft.
There are multiple different systems in place. The most widely-used ones are:
CATOBAR (catapult-assisted takeoff but arrested landing): the airplane spools up its engine(s) to full thrust while being held in place by a restraint system, then gets literally catapulted off the deck with a sled that is attached to the nose wheel gear and “slings” the airplane forward and accelerates it to takeoff speed. For landing, the airplane extends a tail hook that catches a steel wire on the deck which “pulls” the airplane to a stop.
- STOL (short takeoff and landing): some airplanes are capable of normal takeoff and landing on the runway lengths provided by an aircraft carrier. This is mostly no longer in use, but it was the way things worked in WW I and WW II. The world records for STOL airplanes at the moment are about 10 feet for takeoff and under 10 feet for landing.
- VTOL (vertical takeoff and landing): some airplanes are able to take off and land vertically. Some examples are the McDonnell Douglas AV-8B Harrier II “Jump Jet” and the F-35B variant of the Lockheed Martin F-35 Lightning II.
- STOVL (short takeoff / vertical landing): taking off vertically uses a lot of fuel and limits the weight of the airplane (meaning they cannot take as many weapons with them), therefore it is more efficient to have a short takeoff roll and take off with at least some forward speed.
Ski Jump: at the end of the deck, the very end of the runway is curved upward, this gives the airplane additional upward momentum and accelerates it upwards into the air. Typically used for STOVL airplanes. The most well-known examples are the British aircraft carriers of the last decades.
In all of these different modes, the aircraft carrier can always do two things that an airport cannot do:
- The carrier turns directly into the wind (or in case of an angled flight deck at such an angle that the runway points directly into the wind). That means, an airplane never has to worry about taking off with a crosswind or tailwind, it will always have a headwind, which increases the airspeed.
- The carrier accelerates to its highest sustainable speed. So, even if there is no wind, the airplane already has some forward velocity relative to the airflow.
Landing on an aircraft carrier
Similar to takeoff, landing an aircraft involves the work of several machines aboard the ship, in addition to monitoring by ground crewmen.
To land a plane, the pilot flies over the flight deck and attaches a hook on the plane to a steel wire on the ship, called the arresting wire. The arresting wire is attached to a hydraulic system that slows the plane down. It can stop the plane in a distance of 300 feet. There are four such wires on the ship, but pilots always try to catch the third wire because it’s safest.
Furthermore, because the landing strip is so short, landing a plane requires close communication between the pilot and ship crew.
When multiple planes await landing, they fly in an oval formation. One by one, air traffic control gives the planes clearance to land.
If a plane is not on target for landing, the landing signal officer (LSO) can use radio or light signals to redirect the plane. The LSO can request that the plane abort a landing attempt.
Pilots are also directed to the flight deck by the Fresnel Lens Optical Landing System (FLOLS). FLOLS is a collection of lenses that produces light beams at different angles. The different lights beams inform the pilot about his or her position relative to the aircraft.
In particular, if the pilot sees an amber light in line with a series of green lights, then the plane is correctly aligned with the runway.