An aircraft assembly comprising: one or more landing gear each arranged to be movable between a stowed condition for flight and a deployed condition for take-off and landing, the landing gear having a known deployment value; landing gear deployment apparatus for permitting the landing gear to move from the stowed condition to the deployed condition; landing gear down-lock sensing apparatus for detecting that the landing gear has assumed the deployed condition and providing a down-lock signal indicative of the landing gear having assumed the deployed condition; an aircraft navigation system for providing aircraft position relative to a target runway and aircraft speed information; an aircraft landing gear control system for providing a deploy signal to the landing gear deployment apparatus to deploy the landing gear and receiving the down lock signals from the landing gear sensing apparatus; an aircraft flight control system; and a landing gear deployment controller communicatively coupled to the aircraft navigation system, the aircraft landing gear control system and the aircraft flight control system, the landing gear deployment controller being configured to: calculate a touch down value using the aircraft position and speed information provided by the aircraft navigation system; command the aircraft landing gear control system to provide the deploy signal when the touch down value reaches a deployment threshold which is greater than the landing gear deployment value; and command the aircraft flight control system to execute a landing abort sequence if the controller does not receive the down-lock signal from the landing gear sensing apparatus before expiry of a down-lock value which is greater than or equal to the deployment value for the landing gear but less than the touch down value. one or more landing gear each arranged to be movable between a stowed condition for flight and a deployed condition for take-off and landing, the landing gear having a known deployment value; landing gear deployment apparatus for permitting the landing gear to move from the stowed condition to the deployed condition; landing gear down-lock sensing apparatus for detecting that the landing gear has assumed the deployed condition and providing a down-lock signal indicative of the landing gear having assumed the deployed condition; an aircraft navigation system for providing aircraft position relative to a target runway and aircraft speed information; an aircraft landing gear control system for providing a deploy signal to the landing gear deployment apparatus to deploy the landing gear and receiving the down lock signals from the landing gear sensing apparatus; an aircraft flight control system; and a landing gear deployment controller communicatively coupled to the aircraft navigation system, the aircraft landing gear control system and the aircraft flight control system, the landing gear deployment controller being configured to: calculate a touch down value using the aircraft position and speed information provided by the aircraft navigation system; command the aircraft landing gear control system to provide the deploy signal when the touch down value reaches a deployment threshold which is greater than the landing gear deployment value; and command the aircraft flight control system to execute a landing abort sequence if the controller does not receive the down-lock signal from the landing gear sensing apparatus before expiry of a down-lock value which is greater than or equal to the deployment value for the landing gear but less than the touch down value. calculate a touch down value using the aircraft position and speed information provided by the aircraft navigation system; command the aircraft landing gear control system to provide the deploy signal when the touch down value reaches a deployment threshold which is greater than the landing gear deployment value; and command the aircraft flight control system to execute a landing abort sequence if the controller does not receive the down-lock signal from the landing gear sensing apparatus before expiry of a down-lock value which is greater than or equal to the deployment value for the landing gear but less than the touch down value.