Method of monitoring the pressure of an aircraft tire

1. A system for monitoring the pressure of a tire of an aircraft, the system comprising:

a sensor system comprising a hand-held computing device including a display device, and a pressure sensor for taking pressure readings from the tire at each of two or more different points in time and wirelessly transmitting the measured pressures to the hand-held computing device;

wherein the hand-held computing device is configured to calculate a deflation rate based on two or more of the pressure readings and to display an alert on the display device if the rate of deflation is greater than a threshold rate of deflation.

2. The system of claim 1 , wherein the sensor system comprises a temperature sensor for taking temperature readings, wherein the deflation rate is calculated by normalising each pressure reading based on an associated temperature reading from the temperature sensor and a common reference temperature to obtain a temperature-normalised pressure reading, and the computer system is configured to calculate the deflation rate based on the temperature-normalised pressure readings.

3. The system of claim 2 , wherein the computer system is configured to estimate a time for the tire to deflate to a reference pressure level.

4. The system of claim 2 , wherein the computer system is configured to estimate a pressure at a destination, compare the estimated pressure at the destination with a second threshold, and provide a warning if the estimated pressure at the destination is less than a second threshold.

5. The system of claim 1 , comprising a plurality of sensor systems such that each wheel of the aircraft has an associated sensor system.

6. A method to monitor a gas pressure in a tire of an aircraft, the method comprises:

measuring a pressure of a gas in the tire of the aircraft at each of two or more different points in time;

wirelessly transmitting the measured pressures to a hand-held computing device;

calculating by the hand-held computing device a rate of deflation of the tire based on the measured pressures and the points in time at which the measurements were performed, and

displaying an alert on a display device associated with the hand-held computing device if the rate of deflation is greater than a threshold rate of deflation.

7. The method of claim 6 , further comprising calculating a time for the tire to deflate to a reference pressure level based on the deflation rate.

8. The method of claim 7 further comprising displaying the time for the tire to deflate to the reference pressure level.

9. The method of claim 7 , wherein the time for the tire to deflate to the reference pressure level is calculated by reducing a selected one of the pressure readings with respect to a lower temperature to obtain a temperature-adjusted pressure level, and calculating a time for the tire to deflate from the temperature-adjusted pressure level to the reference pressure level based on the deflation rate.

10. The method of claim 6 , further comprising calculating a first time for the tire to deflate to a first reference pressure level based on the deflation rate, and calculating a second time for the tire to deflate to a second reference pressure level based on the deflation rate.

11. The method of claim 10 further comprising simultaneously displaying the first and second times on a single display device.

12. The method of claim 6 , further comprising for each pressure reading taking an associated temperature reading, wherein the deflation rate is calculated by normalising each pressure reading based on its associated temperature reading and a common reference temperature to obtain a temperature-normalised pressure reading, and calculating the deflation rate based on the temperature-normalised pressure readings.

13. The method of claim 6 , wherein the deflation rate is calculated based on three or more pressure readings taken from the tire at different times.

14. The method of claim 6 further comprising:

measuring a temperature of the gas in the tire at each of the two or more different points of time;

calculating by the hand-held computing device, for each of the two or more different points of time, an adjusted pressure in the tire based representing a predicted gas pressure in the tire for the gas at a reference temperature, wherein the reference temperature is used to calculated the adjusted pressure for all of the two or more different points of time, and

the calculation of the rate of deflation is performed using the adjusted pressures each corresponding to one of the two or more different points of time.