By Dr Terry Kahuma
As a young kid, whenever a person asked me what I wanted to be when I grew up, I would tell them “a pilot”. Till now, I marvel at how a huge vessel like an airplane is able to rise up, with so much weight, and soar the sky.
Fortunately, in my working life, I’ve been able to fly all over the world, to all continents, logging so many hours in my object of fascination. Some flights have been so long that, including long transit times, up to two or three days have passed and the first question I ask when I land is “which day of the week is it”?
A workmate of mine was so tired when he flew to the United States that he boarded a different connecting local flight and had to be assisted to board a totally unscheduled flight to his proper destination.
On one such flight, before terrorism became such a menace, as I waited for the flight to take off, I sauntered into the cockpit and asked the pilot how the plane flies all the way from Entebbe to say Amsterdam deep in the night, and even land when the pilot cannot use ordinary vision.
He told me that the on-board computers together with the GPS (global positioning system) are able to guide the flight towards the destination once the pilot enters the co-ordinates of the destination airport. Moreover, the computer operated navigation system works out the safest, most economic and most convenient route, within the confines of permission to overfly certain countries, allowable altitudes, avoidance of war zones, and taking into account other flights operating at the time.
I have since established that the GPS system is anchored on signals emitted by orbiting communication satellites which house very accurate atomic clocks which send signals continuously to a receiver in the aircraft. The receiver, aided by computers, uses the time difference in the signals sent by at least 6 of the satellites to calculate the aircraft’s position.
This determination is coupled together with the output of the IRS (Inertial Reference System) which comprises three laser gyroscopes positioned at right angles to each other and are able to detect any azimuthal movement of the plane. The on-board computers translate this into translational movement on the ground.
The plane’s Flight Management Computer takes the positions computed by the GPS and IRS and computes the actual location of the aircraft which is updated 30 times a second. Through this process, the pilot knows exactly where he/she is at any time. By the aid of other detecting and measuring devices, the forces exerted by wind are also taken into account to guide the plane accurately to the desired direction.
When other flights are using the airspace in the same area, the flights are allocated different altitudes to avoid collisions. Computers in these different flights even “talk” to each other so that when they “feel” that a collision is imminent, one becomes master and the other a slave, and the slave gets directed to move higher or lower.
Computers store all operations and communications on the flight into a data recorder and a flight recorder or black box, so as to guide investigations if an accident occurs.
Flying has been made quite a safe mode of travel by extensive use of ICT to aid navigation and flight operation, considering the low accident rate compared with the huge volume of passenger traffic.
ICT use in aviation extends to booking, scheduling, flight control, payments, radar operation, weight determination, balance of the aircraft, loading, altitude measurement, instrument landing, communication to ground-based beacons, communication to ground-based stations, instrument readings and display, warning signals, fire detection, engine performance monitoring, emergency operation, cargo tagging and tracking, etc.
All these were once only manually operated, and it is difficulty to appreciate just how pilots managed without the aid of ICT. When we study ICT, we advance the boundaries of such a wonderful industry and contribute massively to easing travel and cargo transportation.
Dr.Terry Kahuma is the Dean Faculty of Science and Technology at Victoria University Kampala