If 4 to 6 sets of 4 coach trains are specifically alloted to airport connectivity, this can be done.
There should be an hourly train from WFD, BNC and SBC round the clock. Schedule should be adjusted in such a way that every 30 minutes, there will be a train from YNK to airport.
For example,
SBC 0600...
more... YPR 0615 YNK 0645 KIAL 0715.
Next BNC 0630 YNK 0715 KIAL 0745
Next WFD 0615 KJM 0700 YNK 0745 KIAL 0815.
Same way, every 30 minutes, a train to YNK and then they go towards SBC/ WFD/ BNC alternately.
Cycle continues.
So, you have a train every 1 hour from SBC/ BNC/ WFD and once in 30 minutes from YNK.