Atlas / Learn / Glossary IM — ILS inner marker IM · Abbreviation ILS inner marker. Source: 14 CFR § 1.2 Related · Abbreviation ABEAM ABEAM ABORT ABORT — To terminate a preplanned aircraft maneuver AFM AFM — airplane flight manual AGL AGL — above ground level ALS ALS — approach light system APU APU — auxiliary power unit
