Difference between revisions of "Carrier Air Operations"

Revision as of 14:11, 10 December 2018

A home away from home for many naval aviators

Carrier Air Operations are the various procedures and techniques that make up landing on a moving ship, usually several miles away from any solid ground on which you can land instead. Both fixed-wing and rotary wing aircraft can make use of aircraft carriers to land on, as well as STOL / STOVL aircraft such as the Harrier and the F-35B. Because of the relatively small size (compared to a fully fledged land-based airport) of the carrier, strict procedures and rules are employed to avoid accidents (such as airplanes crashing into one another).

Carrier Basics

Before we dive headfirst into the procedures and rules associated with carrier air operations, we will first go over the various basics that come into play when operating on a carrier. These include items such as how does a carrier work, what does a carrier look like, and what sort of key features should you pay attention to when you cannot make out left from right when operating on a busy carrier.

Carrier Features

Simply put an aircraft carrier is a floating airfield for naval aviators (pilots in the Navy and the Marine Corps) to take-off and land when doing their missions. Normally an airplane can use a fully sized runway for taking off or landing, with the size of these runways landing somewhere in the ballpark of 6000 - 12000 feet. For obvious reasons we cannot have a ship that is that long, so all manner of studies and experiments have allowed us to reduce the size of the runway needed for carrier planes. This started all the way back to the early 1900's, though the carrier became a main staple just prior to / with the beginning of the Second World War.

Arresting gear

F-18C landing with arrestor wires

Early carriers and carrier planes were remarkable similar to the ones used for conventional landing on airfields and airstrips, but as planes got bigger and started carrying more ordinance (torpedo's, rockets and bombs) the increase in weight meant that the airplanes could not be stopped in time or slow down enough to safely land on the carrier.

A rather simple but ingenious solution was devised: they would span a number of wires (3 ~ 4) across the deck, and bolt a hook to the aircraft that could catch these wires. As soon as a landing aircraft trapped one of these arrestor wires it would slow down rapidly and be landed safely (although decelerated quite harshly). This system is still in use today (in a more modern form) and the method used for landing all fixed-wing aircraft on the carrier. STOL/STOVL (such as the F-35) and helicopter aircraft obviously do not require the arresting wires, as they can land (semi) vertically on the carrier deck.

Arrestor wires function by having an pneumatic system limit the rate at which the amount of wires can be pulled out (dissipating the energy in a controlled fashion). Typically a large hydraulic ram is used that forces fluid through a small diameter hole, so that it slows the aircraft (smoothly) down more the more wire is pulled out. In the early days a barrier (basically a large and strong net) was used as a backup for when an aircraft would fail to trap any wire; nowadays they are reserved for emergencies only.

To faciliate the trapping of planes on carriers they have to be equipped with a hook to catch (or trap) one of the wires (typically up to 5 wires are used on carriers): because the landings are also tougher on the undercarriage of the airplanes, most naval based aircraft also have a much sturdier and bigger gear to be able to withstand the shock of landing on the carrier.

Prior and shortly after the invention of the arrestor wires, the deck was typically rectangular in shape, meaning aircraft landing where in direct conflict with aircraft taking off (so it could not be done at the same time). It was not until the early 70's that they invented the angled landing deck, so that landing aircraft were offset by several degrees from the catapults and aircraft taking off; from then on both recoveries and takeoffs could be performed simultaneously.

Ski ramps (STOBAR)

Su-33 taking on from ski carrier ramp

In the early days of the carrier (World War 2) most carriers were ships over which a flat deck superstructure was built, to be used by the air carrier wing (planes). Even after being equipped with the previously mentioned arrestor gear and barrier, the take-off procedure was unceremoniously going to full power and simply leaping off the edge of the carrier going at full till. This was possible because of propeller planes having a high thrust-to-weight ratio: they put out a high amount of power whilst the total weight of the aircraft is relatively low.

The introduction of jet engines, heavy electronic equipment (radar, targeting sensors) and various types of air-to-air and air-to-ground weaponry meant a significant increase in overall aircraft weight. As such, fixed wing aircraft lost their high thrust-to-weight ratio and could not reliably take off under their own power any longer. The Russians / Soviet bloc adapted a stratagem of high thrust engines combined with weight restrictions and mandated lower overall weight of their aircraft; they also adopted the ski ramp on their carriers.

Ski ramp on a Russian carrier

Visually and effectively similar to a ramp one might see at a ski resort, the planes line up on the designated positions on the carrier and removable chocks come up from inside the carrier deck to hold the aircraft in place. The JBD (Jet Blast Deflectors) are raised behind the aircraft to allow for maximum (afterburning) power to be used: the JBD prevent aircraft from being blown off the aircraft deck. Some naval jet aircraft (particularly those of Russian variety) may have an additional engine power override mode reserved for use with carrier takeoffs.

The ski ramp increases both the altitude (though marginally) and the Angle of Attack / attitude of the aircraft launched: the particular combination allows an aircraft with a high thrust-to-weight ratio to become airborne under its own power (there is no requirement on an external power source). The ramp itself also requires significantly less maintenance (and cost) than the contemperary CATOBAR system used by most NATO countries and the US.

The largest drawback of the STOBAR ( Short Take-Off But Arrested Recovery ) ramp system overall is the reduced weight an aircraft can field, limiting the amount of weapons and fuel that can be brought with on a departure from the carrier (though refueling is commonplace after taking off from the carrier). Another drawback is the reduced size of the usable carrier deck, as you can't park aircraft on the ramp.

Catapults (CATOBAR)

F-18C taking off using the catapult

Rather than implement the CATOBAR ramp system, the United States (whom pioneered the system) and most NATO countries instead use the CATOBAR (Catapult Assisted Take-Off But Arrested Recovery system. The aircraft catapult is a launcher to which an aircraft is hooked up, which is then launched using external power from the carrier (either steam or electromagnetic power).

Up to the Cold War most aircraft used a length of reinforced rope (called a bridle) to attach to the catapult shuttle, but in all aircraft after the Cold War the shuttle instead connects to the nose gear of the aircraft via the launch bar. The pilot can selectively lower the launch bar with a switch in the cockpit to hook up to the catapult (shuttle). This shuttle also holds back the aircraft, so that the engines can be run up to full (afterburning) mode before launching. Once the bar is released remotely by the shooter (the officer in charge of the catapult) the aircraft soars away off the end of the deck and hopefully into the sky.

Carrier Deck Layout

Carrier decks can be quite busy with both player and non-player controlled aircraft, so before we step on the busy boat, it imight be a good idea to familiarise ourselves with the overall carrier layout. Due to the relatively small size and large amount of traffic it can often feel cramped on the boat, so knowing where you are going would be wise.

As you can see there a number of different areas on the carrier that each have their own name within the carrier jargon. The figure shown here is a diagram of the USS Nimitz class carriers, but these area names should still apply across all carriers (even non-NATO carriers such as the Admiral Kuznetsov) to indicate where you are on the carrier deck.

The mission developer can choose to include a number of static objects (parked aircraft, munition carts) on the carrier deck as well: they will not be moving, but they are collideable should you run into them. Typically they will be put off to the side, but ensure that your catapult is not blocked prior to your take off attempt.

The most prevalent locations and features should be the catapults (numbered and marked in green) and the landing deck area (between the red stripes), which is where the arrestor wires are. In general it would be a good idea not to block these area (for any longer than absolutely necessary), lest you run into someone taking off or coming in for a landing. Typically you should have approximately 20 to 30 seconds interval between departures and landings, but try to stay alert and mindful of others. Lets break down the areas:

1. Landing Deck (between the red lines, with yellow centerline): This area is typically reserved for aircraft coming in to land, and if you thus need to cross it, ensure that there is no aircraft about to land. Cross quickly, and apologize to the poor sod who's landing you just interrupted. Note that the landing deck is offset (by approximately 9° from the carrier's course heading; the carrier heading itself is called the BRC (Base Recovery Course).
2. Catapults (in green): The catapults are used for taking off from the carrier (so try not to block them, either). Please note that catapult 1 and/or 2 may be regularly blocked by parked aircraft, as otherwise we can not all fit on the tiny carrier; catapult 3 & 4 meanwhile happily block the landing deck area when an aircraft is attached. Each catapult has its own JBD (Jet Blast Deflector), to avoid scorching other planes and/or blowing them overboard: they are raised automatically when you hook up to the catapult, but give them a second to extend fully before ramming that throttle forwards.
3. The Island (in purple): This is where all the important people sit, such as the air marshall / boss (in control of the air traffic), as well as the captain (who steers the boat).
4. Elevators (in blue): The elevators are used to ferry aircraft to above and below deck at the respective beginning and end of missions.
5. Crotch: This area should not be used for parking either; typically on landing your velocity vector will point on this area (but do not land by pointing your velocity vector in this area, use the IFLOLS instead!).
6. Box: The box houses the catapult officer (in charge of operating the catapults); there is a little cabin that raises out of the deck where the officer sits so he does not get wet (or get blasted by the aircraft).
7. Point: The point is normally reserved for parking quick-reaction flights (such as CAP support), as this area gives the quickest and easiest (unhindered) access to catapults (1 & 2). Aircraft parked here may be hot-aligned to allow for quick response.
8. Corral: It is a parking area between elevator 1 and 2, a nice calm place to survey the busy chaos that is the typical carrier deck.
9. Street: This area is not meant for parking, but is instead a transit area serving the corral, elevator 1&2, as well as the sixpack. So try not to block it.
10. Sixpack: Any landed aircraft will typically be directed to the sixpack for shutdown, or prior to taxiing to their final parking place. Threat it as a holding area of sorts: please note that if in the sixpack you can easily block the landing deck area, so take care to position yourself properly or you may find yourself missing your tail section / rudders / elevators.
11. Junkyard: This is where they normally park the E-2 Hawkeye (AWACS) and C-2 Greyhound (cargo) aircraft, as well as the crane used for removing crashed aircraft and debris. Because these always looks like pieces of junk, this area is named the junkyard.
12. Patio: A place that is far away from all the chaos on the carrier deck and gives you a nice view of aircraft trying to stick the landing on the landing deck area.
13. LSO: This is where the guys sit that determine if you are within the Case 1/2/3 parameters and get to make it aboard, or if you have to wave off again and join the back of the line in the pattern before you get to try landing again.
14.Finger: This parking area, aptly named for the gesture you may wish to make to their nearby LSO for waving you off again, requires you to taxi to the other end of the ship and inconvenience everyone on the way before you make it to where the catapults are.

Carrier Cases

During carrier operations we use 1 of 3 possible cases, with cases each having different approaches and procedures: this is to adjust to the weather and visibility conditions. The carrier will normally dictate which case is currently in use, but mainly it is dependant on the minimum visibility ('horizontal sightlines') and ceiling ('vertical visibility') according to the table below:

Case	Conditions	Ceiling	Visibility
1	No instrument conditions during daytime departures/recoveries	> 3000 ft (910 m)	> 5 nm (9.3 km)
2	(Light) Instrument conditions during daytime departures/recoveries	> 1000 ft (300 m)	> 5 nm (9.3 km)
3	Severe instrument conditions during daytime and nighttime recoveries	< 1000 ft (300 m)	< 5 nm (9.3 km)

Please note that recovering during night time automatically defers you to a case 3 landing, regardless of actual weather and visibility conditions.

Altitudes, ranges and distances

The Air Traffic Controller in charge of the flight procedures around the carrier is called the 'Marshall', and he gets to boss you around for not flying perfectly perpendicular to his nice pattern / approach. He will tell you what case the carrier is currently operating in, gives you permission to transition to a given holding stack (altitude) or move closer to the carrier (zone).

Most notably the Marshall should tell you the BRC, or Base Recovery Course. This the current course that the carrier is moving in, and should be the course that you adhere to for landing your aircraft on the carrier deck: please note that the actual carrier landing deck is offset by 9 degrees from the BRC.

Below are the altitude blocks and zone distances associated with carrier operations:

Altitude	Zone
6000+ ft	Case 3 Marshall (traffic) stack
3000+ ft	Case 1 holding pattern / stack
1200 ft	Case 3 approach and missed approach
800 ft	Case 1 initial overhead break
600 ft	Case 1 downwind and missed approach
500 ft	Case 1 departure in CCZ
300 ft	Helicopter operations in CCZ

Distance	Altitude	Zone
50 nm DME	Inf.	CCA, Carrier Controlled Area
10 nm DME	Inf.	Marshall Controlled Area
5 nm DME	2500 ft	CCZ, Carrier Controlled Zone

Distances given in DME (Distance Measuring Equipment) are thus identical to distance from the carrier: this distance can be obtained by using the TACAN signal of the carrier or similar equipment (ICLS).

Carrier TakeOff

Carrier Landing

For this chapter we have outline the various carrier cases landing procedures and approaches: for ease of use these are split into the traffic pattern and landing pattern. The traffic pattern is used for approaching to the carrier and holding the in the traffic pattern / stack until you it is your time to land on the carrier (which usually involves waiting for other pilots to land first). The landing pattern goes about explaining the actual steps for the landing approach. Thanks to Koala360 we have also been able to provide you with the relevant communications guide for these cases.

We would like to give a massive 'Thank you' to Jabbers, Koala360 and Redkite for their contributions to making these chapters.

Case 1 Landing

Case 1 Traffic Pattern

As mentioned previously the traffic pattern is used for holding until you are cleared for landing on the carrier. For Case 1 the traffic pattern is a circle holding pattern with a diameter of approximately 5 nautical miles (9.3 km, 5.8 mi) which you are supposed to fly at roughly 250 kts (463 km/h, 287 mi/h), but this does not need to be exact.

You do need to absolutely adhere to 1. Flying the Traffic Pattern circle anti-clockwise and 2. Maintaining your assigned altitude. Both are to prevent you from hindering or crashing into other aircraft. As to the altitude, each flight / package (set of aircraft for a given tasking) gets assigned a altitude at 1000's of feet starting at 3000 feet. That means if you are the 4th flight currently arriving in the traffic pattern, you and your wingmen should expect to maintain an altitude of 7000 feet. If slots open up below you, descend to the appropriate position in the stack (queue) depending on instructions from the Marshall (carrier).

Case 1 Landing Pattern

Pattern	F-14	F-18
A	800 ft entry, approx. 300 - 350 kts, hook down, wing sweep 68	800 ft entry, approx. 300 - 350 kts, hook down
B	Speedbrake[1], radar altimeter to 370 ft
C	Level break at 1.5 ~ 2.0 nm DME; 15 to 17 seconds between breaks, level turn at 800 ft. Turn should be at 45 ~ 50 degrees of bank or at 10% in A of airspeed (i.e. 330 kts -> 3.3 G)
D	Halfway into turn, set gear down at < 280 kts and flaps/slats at < 225 kts	Halfway into turn, set gear/flaps/slats at < 250 kts
E	Descend to 600 ft, auto throttle[1]
F	On-speed AOA at 15 units, set DLC	On-speed AOA at 8units
G	600 ft
H	Prepare to turn once abeam of LSO station, at 1 ~ 1.3 nm abeam DME
I	Commence turn once 'round down' visible, turn at ~ 30 degrees bank
J	Maintain AOA, halfway into turn at 500 ft
K	Enter groove at ~ 350 ft (altimeter!), at 3/4 miles, on-speed and call the ball: side number, tomcat/hornet, ball/clara[2], fuelstate[3], (auto[4])
W	Upon (or prior to) waveoff set full power: return to BRC parallel and intercept pattern at LSO / marshall discretion

Speedbrake / ATC [1]		As desired
Clara [2]		Ball is obscured, LSO will give instructions
Fuelstate [3]		Remaining fuel in thousands of pounds: 5100 pounds -> 5.1
Auto [4]		Auto throttle is engaged

Case 2 Landing

Case 3 Landing