At the present time , the Pakistan air force has one air chief marshal, 9 air marshals and 39 air vice marshals. do you know how many Air Commodores were there in his day? and should they have all been promoted? do you people let go of any opportunity to criticize Pakistan forces using nonsensical logic and argument?
BTW Gen Zia ul Haq declared martial law in 1977 and became head of state in 1978 when Sayyad Sajjad Haider was just 2 years away from retirement. I highly doubt that either one knew the other, let alone Zia going around hunting Shia Muslims in the air force to deny them promotions. he was busy fighting Soviets while sectarian scum were busy with civil war!