I made I Plane and When I Press T I want the Speed to Gain +30 Speed ??

                function fly(m) -- Main function that controls all of the flying stuff. Very messy.
                    flying = true
                    local pos,t = main.Position,time()
                    local lastStall = false
                    while ((flying) and (not dead)) do
                        realSpeed = ((pos-main.Position).magnitude/(time()-t))  -- Calculate "real" speed
                        pos,t = main.Position,time()
                        local max = (maxSpeed+(-main.CFrame.lookVector.y*speedVary))    -- Speed variety based on the pitch of the aircraft
                        desiredSpeed = (max*(on and throttle or 0)) -- Find speed based on throttle
                        local change = (desiredSpeed > currentSpeed and 1 or -1)    -- Decide between accelerating or decelerating
                        currentSpeed = (currentSpeed+(accel*change))    -- Calculate new speed
                --      local throttleNeeded = 
                        local stallLine = ((stallSpeed/math.floor(currentSpeed+0.5))*(stallSpeed/max))
                        stallLine = (stallLine > 1 and 1 or stallLine)
                        panel.Throttle.Bar.StallLine.Position = UDim2.new(stallLine,0,0,0)
                        panel.Throttle.Bar.StallLine.BackgroundColor3 = (stallLine > panel.Throttle.Bar.Amount.Size.X.Scale and Color3.new(1,0,0) or Color3.new(0,0,0))
                        if (change == 1) then
                            currentSpeed = (currentSpeed > desiredSpeed and desiredSpeed or currentSpeed)   -- Reduce "glitchy" speed
                        else
                            currentSpeed = (currentSpeed < desiredSpeed and desiredSpeed or currentSpeed)
                        end
                        local tax,stl = taxi(),stall()
                        if ((lastStall) and (not stl) and (not tax)) then   -- Recovering from a stall:
                            if ((realSpeed > -10000) and (realSpeed < 10000)) then
                                currentSpeed = realSpeed
                            else
                                currentSpeed = (stallSpeed+1)
                            end
                        end
                        lastStall = stl
                        move.velocity = (main.CFrame.lookVector*currentSpeed)       -- Set speed to aircraft
                        local bank = ((((m.ViewSizeX/2)-m.X)/(m.ViewSizeX/2))*maxBank)  -- My special equation to calculate the banking of the plane. It's pretty simple actually
                        bank = (bank < -maxBank and -maxBank or bank > maxBank and maxBank or bank)
                        if (tax) then
                            if (currentSpeed < 2) then  -- Stop plane from moving/turning when idled on ground
                                move.maxForce = Vector3.new(0,0,0)
                                gyro.maxTorque = Vector3.new(0,0,0)
                            else
                                move.maxForce = Vector3.new(math.huge,0,math.huge)  -- Taxi
                                gyro.maxTorque = Vector3.new(0,math.huge,0)
                                gyro.cframe = CFrame.new(main.Position,m.Hit.p)
                            end
                        elseif (stl) then
                            move.maxForce = Vector3.new(0,0,0)  -- Stall
                            gyro.maxTorque = Vector3.new(math.huge,math.huge,math.huge)
                            gyro.cframe = (m.Hit*CFrame.Angles(0,0,math.rad(bank)))
                        else
                            move.maxForce = Vector3.new(math.huge,math.huge,math.huge)  -- Fly
                            gyro.maxTorque = Vector3.new(math.huge,math.huge,math.huge)
                            gyro.cframe = (m.Hit*CFrame.Angles(0,0,math.rad(bank)))
                        end
                        if ((altRestrict) and (main.Position.y < altMin)) then  -- If you have altitude restrictions and are below the minimun altitude, then make the plane explode
                            plane.AutoCrash.Value = true
                        end
                        updateGui(tax,stl)  -- Keep the pilot informed!
                        main.Throttle.Value = throttle 
                        wait()
                    end
                end