[...] pamo tinha avian ki sa ta koreba na kel tenpu.
[...] because there were planes that used to fly at that time.
The situation seems fairly complex. If sa ta is viewed as two markers, one for aspect and the other for modality, then the order is ASP-MOOD-V+ANT, but if sa ta is analyzed as a variant of sta, then all we have may be ASP-V+ANT. The jury is still out on this matter.