Watching videos of jets taking off from a carrier, it appears the pilot is holding a hand grip as the jet is catapulted along the deck; then there is 'jerk' type motion as the jet leaves the deck with the pilot then taking control. Could you please describe what happens during the take off. It looks like a really rough ride for the pilot.
A carrier aircraft launcher is called a "catapult", for good reason! It's job is to get an aircraft up to flying speed very quickly, which of course results in a very high acceleration for the plane and pilot. Sometimes as high as 4G.
On modern American aircraft carriers, the catapult is about 300 feet (90 metres) long, and can get a large plane up to flying speed, 140 knots, in about 2 seconds. By comparison, taking off on a conventional runway a plane might need 2 kilometres to get up to this speed.
As you can imagine this puts a lot of stress on the planes, carrier aircraft are built much more rugged than an aircraft that would only fly off normal runways.
Each catapult-launched aircraft has different procedures for launch. In the case of the F/A-18, the pilot keeps his hands off the control column during the actual launch, grabbing it as soon as the plane leaves the edge of the deck. This is not the case for other carrier aircraft, such as the C-2 Greyhound, nor is it the case when taking off the same aircraft from a runway.
I found this in the F/A-18E/F flight manual (PDF here):
Immediately after the end of the catapult stroke, the aircraft will rotate to capture the 12° reference AOA (hands-off). To avoid PIO with the FCS, do not restrain the stick during catapult launch or make stick inputs immediately after catapult launch. The pilot should attempt to remain out of the loop but should closely monitor the catapult sequence.
AOA = Angle of Attack, PIO = Pilot-induced oscillations, FCS = Flight Control System.
Which roughly translates as "The plane will fly itself and find the optimal climb angle without pilot input during the launch."
What you see here as well as here is the pilot grabbing the handle during takeoff. According to this it is to keep the pilots hands off the controls due to the fact that the natural response to the maneuver would cause the pilot to dive the plane. There is also some discussion on it here which offers a counter point:
No that's not why you hold the towel rack. Yes that inner ear sensation can happen, but that's not why. What about the F-14, or A-7, or literally every other airplane that got shot off the front of an aircraft carrier that required the pilot's hand to be on the stick to fly it away?
The reason you don't touch the stick in an F-18 is because the F-18 is very sensitive to pitch inputs at slow speed in the takeoff configuration. If you ham-fisted it, you could pull too much angle of attack too soon and stall.
All pilots salute to signify they are ready for takeoff. They aren't even supposed to put their arms above the canopy rail to avoid accidental shots. There are hold bars on the throttles of some planes to avoid a situation where the throttles go to idle during the shot. With the introduction of fly by wire the 18 can have a computer controlled launch and the pilot holds the handle during the shot. That jerk you see . . . There is a tremendous amount of pressure on the tires during the launch from down force produced by the elevators. With the 18 you can see that the elevators increase delection gradually during the shot whereas most other launches have the elevators at full deflection throughout the cat shot. As the plane leaves the deck the back of the plane is forced down. If you watch video where the airspeed is visible you will see that it momentarily drops when the plane first leaves the deck.
In the early days of catapault launches they discovered that the pilot could not withstand the inertia of his hand slamming backwards at the time of launch. If that hand is holding the stick, then you end up with a large pull back, and thus a large pitch up, which is deemed to be non-optimal at that stage of the flight.
So some manufacturers added something other than the stick for the pilot to hold during the cat shot. (And the USN procedures have the pilot salute the cat launch controller to show his hand's out of the way.)