500
(Refer to Figure 14.) If the terrain elevation is 1,295 feet MSL, what is the height above ground level of the base of the ceiling?
Cloud layers in a PIREP are found after the 'SK' heading. Height of the cloud base is given in hundreds of feet, then the cloud cover symbol (SCT, BKN, etc.) is given, followed by the height of the cloud tops in hundreds of feet. All cloud heights in a PIREP are MSL.
The first cloud layer was reported by a pilot to have bases at 1,800 feet and tops at 5,500 feet with broken (BKN) cloud cover (a broken cloud layer does constitute a ceiling).
If the field elevation is 1,295 feet MSL and the base of the first cloud layer (BKN) is 1,800 feet MSL, then the base of the ceiling is 505 feet AGL.
1,800 MSL - 1,295 MSL = 505 AGL