My explanation to deficit figures, as I learned it before, without the politics:
1947- payments for DC-6
1949- payments for DC-6
1970- payments for BAC1-11, currency devaluation, from 3+ to 7+ to a dollar
1973- payments for DC-10s
1980 to 82- payments for B742s and A300s
1983 to 85- recession and currency devaluation
1988 -payments for F50 and SD360s
1997- recession and currency devaluation
Politics aside, that's spot on for the reasons for PAL's losses in those years. It's not cheap to buy new planes & train the flight & ground crews on how to use them.
Not sure why PAL picked the Fokker 50 over other similar planes at the time like the ATR 42, Saab 340, or the Dash 8. The Dash 8 actually flew to the Philippines to demonstrate it to PAL in 1984. We know PAL was in dire financial straits at that time; but the F50s arrived in 1987 when PAL began to recover. Maybe the Dash 8's weren't suitable for the Philippines; but the Dash 8's served the "missionary" routes in Canada well.
https://pbase.com/philippineaviation/de_havilland_canada_dhc8102_dash_8_demo_flt_for_pal