A method of testing an aircraft landing gear, the aircraft landing gear comprising: first and second wheels (20a, 20b); a first braking system comprising a first tachometer mounted to the first wheel and configured to generate a first tachometer signal indicating rotation of the first wheel, and a first brake configured to brake the first wheel; a second braking system comprising a second tachometer mounted to the second wheel and configured to generate a second tachometer signal indicating rotation of the second wheel, and a second brake configured to brake the second wheel; first and second tachometer output lines (24a, 24b); a first braking command line associated with the first tachometer output line; a second braking command line associated with the second tachometer output line; and a braking control and monitoring system; characterized in that the method comprising: a. generating a test signal with the first tachometer, wherein the first wheel is not rotating during the generation of the test signal; b. receiving the test signal at the braking control and monitoring system via one of the tachometer output lines (24a, 24b); c. issuing a braking command from the braking control and monitoring system in response to the receipt of the test signal, wherein the braking command is issued via the braking command line (31a, 31b) which is associated with the one of the tachometer output lines (24a, 24b); and d. monitoring a response of the first or second braking system (21a, 21b) to the braking command to test for a cross-connection between the first and second braking systems, a cross-connection being indicated if the second braking system responds to the braking command. first and second wheels (20a, 20b); a first braking system comprising a first tachometer mounted to the first wheel and configured to generate a first tachometer signal indicating rotation of the first wheel, and a first brake configured to brake the first wheel; a second braking system comprising a second tachometer mounted to the second wheel and configured to generate a second tachometer signal indicating rotation of the second wheel, and a second brake configured to brake the second wheel; first and second tachometer output lines (24a, 24b); a first braking command line associated with the first tachometer output line; a second braking command line associated with the second tachometer output line; and a braking control and monitoring system; characterized in that the method comprising: a. generating a test signal with the first tachometer, wherein the first wheel is not rotating during the generation of the test signal; b. receiving the test signal at the braking control and monitoring system via one of the tachometer output lines (24a, 24b); c. issuing a braking command from the braking control and monitoring system in response to the receipt of the test signal, wherein the braking command is issued via the braking command line (31a, 31b) which is associated with the one of the tachometer output lines (24a, 24b); and d. monitoring a response of the first or second braking system (21a, 21b) to the braking command to test for a cross-connection between the first and second braking systems, a cross-connection being indicated if the second braking system responds to the braking command. a. generating a test signal with the first tachometer, wherein the first wheel is not rotating during the generation of the test signal; b. receiving the test signal at the braking control and monitoring system via one of the tachometer output lines (24a, 24b); c. issuing a braking command from the braking control and monitoring system in response to the receipt of the test signal, wherein the braking command is issued via the braking command line (31a, 31b) which is associated with the one of the tachometer output lines (24a, 24b); and d. monitoring a response of the first or second braking system (21a, 21b) to the braking command to test for a cross-connection between the first and second braking systems, a cross-connection being indicated if the second braking system responds to the braking command.