A carrier landing is the only landing in aviation where the pilot pushes the throttles forward at the moment of touchdown. The jet slams onto the deck, the tailhook drags across the steel, and the engines are already screaming at full power. If the hook catches a wire, the aircraft stops in about two seconds. If it does not, the jet simply keeps going, off the end of the angled deck and back into the sky.
That second outcome has a name: a bolter. On the radio it comes as three words from the Landing Signal Officer, "bolter, bolter, bolter", and every naval aviator has heard it about themselves.
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- What it is: An arrested landing attempt in which the aircraft touches down but fails to catch any arresting wire
- What happens next: The pilot, already at full power, flies off the angled deck, climbs to 1,200 ft and joins the bolter/wave-off pattern
- Target wire: The middle wire: the second or third, depending on the carrier
- Wires on a US carrier: Three or four, about 20 ft (6.1 m) apart
- Mark 7 Mod 3 arresting gear: Stops a 50,000 lb aircraft from 130 knots in 344 ft, in about two seconds
- LSO grade: 2.5 for a safe, at least average pass that bolters; 2 for an unsafe or below-average one
- Made possible by: The British angled flight deck, first trialled on HMS Triumph in 1952
Why pilots go to full power on touchdown
In United States Naval Aviation, the pilot aims for the middle arresting wire. On touchdown, the throttles go to military or full power for three seconds. It sounds backwards, but it is the whole safety system: the engines stay spooled up and producing thrust in case the hook misses every wire, or in the unlikely event that a cable snaps.
If the hook catches, the arresting gear absorbs the thrust along with the aircraft's energy, and the pilot pulls the throttles back to idle once stopped. If it misses, there is no time to wait for engines to spool up from idle. The aircraft is already accelerating and rotates off the end of the landing area.
The photo at the top of this article shows the moment in its most dramatic form: an F/A-18C Hornet of VFA-25 on USS John C. Stennis in 2004, sparks flying from its tailhook as full power is applied after a bolter.
How a bolter happens
Most bolters come from landing long: the aircraft is slightly high on the glide slope and touches down beyond the last wire. The hook drags over bare deck and the pilot has no choice but to fly away.
There is also the more frustrating version. Occasionally the tailhook bounces over one or more wires even though the aircraft was in the right place. This is called a "hook skip bolter", and it is one reason the LSO grades the approach, not just whether the jet stopped.
The bolter pattern
Once airborne again, the pilot climbs straight ahead to 1,200 ft and enters the "bolter/wave-off pattern", where the same climb-out is also used for aircraft waved off by the LSO or pulled off the approach because the deck is fouled. Approach control then sequences the aircraft back in behind the others waiting to land.
At night or in bad weather, the recovery is flown under Case III rules. That means another instrument approach to the ship in the dark, with the fuel gauge getting lower each time round. A Super Hornet bolter at night, filmed from the cockpit, shows how little the pilot sees of the deck:
Before the angled deck, there was no going around
On the straight-deck carriers of the Second World War and the early jet age, the landing area ran along the ship's axis. An aircraft that missed the wires could not fly off again, because the forward half of the deck was full of parked aircraft. Instead it was stopped by a barrier that caught its landing gear, or by a net barricade that caught its wings, which often damaged the aircraft and took time to clear.
Jets made the problem worse. They were heavier, came in faster and took longer to respond to the throttle. The British solution was to angle the landing area away from the ship's axis, so a missed landing simply ran off the side of the ship into clear air. It was first tested in 1952 on HMS Triumph of the Fleet Air Arm, using painted markings for touch-and-go landings. From September to December 1952, USS Antietam trialled a rudimentary angled sponson with full arrested landings.
The angled deck turned a missed landing from a crash into a routine go-around. The British were also the first to call it a bolter. By the time heavy jets like the A-3 Skywarrior went to sea, the bolter was just part of the job.
Bolters and carrier qualification
Every naval aviator has to prove they can land on the ship, and bolters are part of that test. Undergraduate carrier qualification for students, flown in the T-45 Goshawk, consists of 14 day landings, at least 10 of them arrested. Initial qualification in a first fleet aircraft such as the F/A-18 requires 12 day landings and eight at night, with minimum numbers of arrested landings in each.
A bolter does not count as an arrested landing, so it does not move the pilot any closer to qualifying. The LSO grades each pass on a scale of 0 to 5. A bolter from a safe, at least average approach is scored 2.5; an unsafe or below-average approach that bolters gets a 2.
When the hook itself is the problem
A bolter is usually the pilot's fault, but not always. During flight testing of the F-35C, the Navy's carrier variant failed to catch the arresting wire in all eight landing tests, and the tailhook had to be redesigned over a two-year period.
If a tailhook is damaged or will not come down, there is no amount of boltering that will help. The pilot either diverts to a shore base if one is in range, or is caught by the emergency barricade, the descendant of the old nets, which is now rigged only for emergencies.
Sources: Wikipedia (Bolter, Arresting gear, Tailhook, Angled flight deck, Modern US Navy carrier air operations), U.S. Navy
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