Flying vehicle

Hello everyone,
Am working on get a jet in the game. But the Jet is hard to control and I need to keep the jet above X and below Y. So the jet will have a range that it can fly in. Here is my datablock:

datablock FlyingVehicleData(F18)
{
spawnOffset = "0 0 1";
category = "Vehicles";
shapeFile = "~/data/shapes/Jets/f18.dts";

ultipassenger = false;
renderWhenDestroyed = false;
mountPose[0] = sitting;
drag = 0.15;
density = 1.0;

cameraMaxDist = 6;
cameraOffset = 1.8;
cameraRoll = true;
cameraDecay = 0.99;
cameraLag = 0.05;

minMountDist = 6;

MaxEnergy = 280;
MinDrag = 88;
RotationalDrag = 10;
RechargeRate = 0.0;

maxAutoSpeed = 4;
autoAngularForce = 100;
autoLinearForce = 300;
autoInputDamping = 0.85;


MaxSteeringAngle = 4.2;
HorizontalSurfaceForce = 350;
VerticalSurfaceForce = 100;
ManeuveringForce = 4500;
SteeringForce = 1500;
SteeringRollForce = 1280;
RollForce = 820;
HoverHeight = 1.0;
CreateHoverHeight = 1.0;

// Rigid body
Mass = 500;
BodyFriction = 0;
BodyRestitution = 0.8;
MinRollSpeed = 0;
MinImpactSpeed = 0;
SoftImpactSpeed = 10;
HardImpactSpeed = 25;
SpeedDamageScale = 0.04;
}

Thanks for any help.