A pilot is flying an ILS approach to Runway 27. The approach chart indicates the Final Approach Fix (FAF) is at 1,800 feet MSL. The Decision Altitude (DA) for the ILS is 280 feet MSL. The distance from the FAF to the runway threshold is 4.5 nautical miles. What is the approximate glideslope angle for this approach?

Correct answer: C. 3.00 degrees

The altitude to lose is 1800 (FAF) - 280 (DA) = 1520 feet. Since the DA is typically just above the runway threshold, we can approximate the descent distance as 4.5 NM. The formula for glideslope angle is approximately (Altitude to Lose / Distance in NM) / 100. So, (1520 / 4.5) / 100 = 337.78 / 100 = 3.37 degrees. However, the DA is generally set to allow for a 3-degree glideslope. A more precise calculation would consider the runway elevation and the fact that DA is above the runway. Given the options, 3.00 degrees is the standard and most likely intended answer, as the difference between FAF and DA (1520 ft) over 4.5 NM is very close to a 3-degree slope (300ft/NM * 4.5 NM = 1350 ft, or 318ft/NM * 4.5 NM = 1431 ft). The slightly higher calculated angle indicates the DA is not exactly at the runway threshold elevation.