the Lightning did eventually get a rad alt, but not when this accident happened. The errors as I recall were at 600 kts, the altimeter overread by 1500ft, so to fly your minimum height at night of 1500ft you set zero on the altimeter. As you decelerated, the error was 1000ft at 550 kts, 700 ft at 500kts, 500ft at 400 kts and 400ft at 350kts. Altimeter finally told the truth at or below 300kts. If you were operating in mach, you subtracted 2 from the subsonic decimal and subtracted that in hundreds of feet from the level you wanted, i.e. Mach 0.9 level at 24,300 ([0.]9-2=7[hundred ft error]) on 1013 to fly at FL 250. Not complicated at all, especially at night, head down the radar scope, listening to a target broadcast and working out your own intercept, all with no NVGs. One week on days, one week on nights, all year round. First winter I shat myself constantly with so much night flying. Loved it after that, what a great aircraft! Don't get me going on the no belly tank christmas present flights with greater than one-to-one thrust at take off!