# A to B With QNH Unchanged MET

With all altimetry problems, the first thing to do is **draw a diagram** and label the levels and vertical distances that you know.

At sea level will be the local QNHQNH —Static pressure at MSL calculated from QFE using ISA temperature lapse rates. The vertical distance of the ground above the sea is the elevation. The vertical distance of the aircraft above the sea is the altitude. The vertical distance of the aircraft above the ground is the height (so height + elevation = altitude). Finally, if the aircraft is at a flight level, you will need to put the level of 1013 in (this could be above or below the sea, depending on what the QNHQNH —Static pressure at MSL calculated from QFE using ISA temperature lapse rates is) and label the flight level distance - the aircraft is (the flight level x 100) feet above the 1013 level.

Once this is done, you can start to answer the question. The vertical distance between any two pressure levels will be 27 x the pressure difference between the two. Once these distances are labelled, look for the unknown you are asked for (this could be height, altitude or a vertical distance above the incorrect QNHQNH —Static pressure at MSL calculated from QFE using ISA temperature lapse rates that was left on the subscale) and use the vertical distances you have got to figure out the answer. There are many common mistakes that can be made - putting the 1013 level the wrong side of the QNHQNH —Static pressure at MSL calculated from QFE using ISA temperature lapse rates, given the answer for height when it asked for altitude and vice versa, or simply