BMI8255
Its as with any other walk of life, no different- If age is linked to fitness to do a job. Some ground jobs demand physical fitness (loaders etc.) other don't, except perhaps the ability to walk from one end of an airport to the other several times a day. The only job I can think of that might have a age limitation might be the Airport Fire Services, if not age then certainly fitness.
Now, whether people will age discriminate in their hiring is another issue. There is some part time but usually full time shift work, you may find seasonal work for the busy summer periods.