Conditions and concepts
AGL is height above the local ground; MSL is altitude above mean sea level. For supplied values, AGL=MSL altitude−terrain MSL elevation. The accompanying figure is an original learning schematic, not an official sectional. Its labels explicitly identify terrain, obstacle top and an illustrative airspace floor. In these supplied schematic exercises, compare aircraft MSL altitude directly with a stated MSL airspace floor; the exercise does not replace actual chart classification or authorization. For these supplied course-conversion exercises, magnetic course equals true course minus east variation or plus west variation. The variation value is explicitly supplied.
Worked decisions
At a site with terrain elevation 800 ft MSL, a drone flies at 1100 ft MSL. What is its height AGL? Subtract the quantities on the same reference: 1100 − 800 = 300 ft AGL. Adding the values would combine the reference with the difference instead of measuring the requested separation. The supported result is 300 ft AGL. Using the original chart-schematic figure: terrain is 900 ft MSL and the obstacle top is 1200 ft MSL. What is the obstacle height above the local terrain? Subtract the quantities on the same reference: 1200 − 900 = 300 ft AGL. Adding the values would combine the reference with the difference instead of measuring the requested separation. The supported result is 300 ft AGL. An original schematic places an airspace floor at 1500 ft MSL. A drone is at 1400 ft MSL. Which numerical relationship is correct? In these supplied schematic exercises, compare aircraft MSL altitude directly with a stated MSL airspace floor; the exercise does not replace actual chart classification or authorization. The supported result is The drone is 100 ft below the floor. A planning exercise gives true course 90 degrees and variation 10 degrees east. Using the stated conversion, what magnetic course results? For this course conversion, subtract the supplied east variation: 90 − 10 = 80 degrees magnetic. No wind-correction model is supplied, so this is a true-to-magnetic conversion only. The supported result is 80 degrees.
A change that matters
At a site with terrain elevation 1250 ft MSL, a drone flies at 1600 ft MSL. What is its height AGL? Subtract the quantities on the same reference: 1600 − 1250 = 350 ft AGL. Adding the values would combine the reference with the difference instead of measuring the requested separation. Here choose 350 ft AGL. Using the original chart-schematic figure: the illustrative airspace floor is 1600 ft MSL and terrain is 900 ft MSL. What is that floor's height above the local terrain? Subtract the quantities on the same reference: 1600 − 900 = 700 ft AGL. Adding the values would combine the reference with the difference instead of measuring the requested separation. Here choose 700 ft AGL. An original schematic places an airspace floor at 1800 ft MSL. A drone is at 1800 ft MSL. Which numerical relationship is correct? In these supplied schematic exercises, compare aircraft MSL altitude directly with a stated MSL airspace floor; the exercise does not replace actual chart classification or authorization. Here choose The drone is at the floor. A planning exercise gives true course 180 degrees and variation 8 degrees west. Using the stated conversion, what magnetic course results? For this course conversion, add the supplied west variation: 180 + 8 = 188 degrees magnetic. No wind-correction model is supplied, so this is a true-to-magnetic conversion only. Here choose 188 degrees.
Transfer check and reasoning
A site is 700 ft MSL and the drone is 1050 ft MSL. Find AGL and explain the reference. 1050−700=350 ft AGL. The subtraction measures height above local ground, not altitude above sea level.
At a site with terrain elevation 800 ft MSL, a drone flies at 1100 ft MSL. What is its height AGL?
- The relevant case condition is: At a site with terrain elevation 800 ft MSL, a drone flies at 1100 ft MSL.
- Subtract the quantities on the same reference: 1100 − 800 = 300 ft AGL. Adding the values would combine the reference with the difference instead of measuring the requested separation.
- Therefore choose “300 ft AGL”. The alternatives must be tested against that same stated condition; an unrelated document, unit or approval cannot supply a missing requirement.
Compare the other answer choices
The proposed choice “1900 ft AGL” does not follow from the given conditions. Subtract the quantities on the same reference: 1100 − 800 = 300 ft AGL. Adding the values would combine the reference with the difference instead of measuring the requested separation.
The proposed choice “1100 ft AGL” does not follow from the given conditions. Subtract the quantities on the same reference: 1100 − 800 = 300 ft AGL. Adding the values would combine the reference with the difference instead of measuring the requested separation.
The proposed choice “800 ft AGL” does not follow from the given conditions. Subtract the quantities on the same reference: 1100 − 800 = 300 ft AGL. Adding the values would combine the reference with the difference instead of measuring the requested separation.
Try it, then explain it.
Complete a short set without looking at the example. After each answer, explain which evidence or rule supports your decision and why the alternatives do not fit.
Sources & authorship
Original Slope explanations and examples. References support the concepts; they are not the source of copied questions. Independent educator review is pending.
Faa Study