Precision approach glide path angle:
1) minimum: 2.5°
2) optimum: 3.0°
3) maximum: 3.5° (3.0° for cat II/III operations).
Procedures involving non-standard glide path angles
Procedures involving glide paths greater than 3.5° or any angle when the nominal rate of descent exceeds 5 m/sec (1000 ft/min), are non-standard and subject to restrictions ("Height loss/altimeter margins"). They are normally restricted to specifically approved operators and aircraft, and are promulgated with appropriate aircraft and crew restrictions annotated on the approach chart.