QNH, QFE, QFF & QNE Explained Simply — Part 3 | DGCA CPL ATPL Meteorology Ch 2 | Sleepy Notes

JOIN THE WHATSAPP STUDY GROUP https://chat.whatsapp.com/I2QqbK812nA... Doubts, discussion, free notes. INSTAGRAM @capt.coalfield | @idk.akarsh Chapter 2 — Atmospheric Pressure, Pressure Systems & Altimetry | PART 3 Part 1 built pressure from the ground up. Part 2 put it on the weather map. This part gets to the instrument on your panel. Your altimeter does not measure height. It measures pressure, then guesses the height using an atmosphere that does not exist. Once that lands, the four settings stop being four things to memorise and become four sensible answers to four different questions. Reference: ICJ (IC Joshi Meteorology), Chapter 2. ═══ COVERED IN PART 3 ═══ PRESSURE GRADIENT Horizontal rate of change, perpendicular to isobars, High to Low Isobars close together = steep = strong wind. Far apart = weak. Gradient sets the wind's SPEED, Coriolis sets the DIRECTION THE "ISO-" FAMILY Isobar, Isotherm, Isallobar, Contour/Isohypse — plus Isogonal and Isoclinal, the two Navigation lines DGCA slips into Met papers CONTOURS AND THICKNESS Why surface charts plot pressure but upper-air charts plot height Contour intervals — 40 gpm at 700 and 500 hPa, 80 gpm at 300 and 200 hPa Geopotential metre — what it is, and why you can treat it as a metre THICKNESS is really a THERMOMETER. Warm air stretched = high thickness. Cold air squashed = low thickness. TENDENCY AND ISALLOBARS Isobar = where pressure IS. Isallobar = where it is GOING. Isallobaric Low — surface Lows move towards it and intensify Why India works tendency over 24 hours, higher latitudes over 3 MEASUREMENT Mercury barometer, aneroid barometer, altimeter, barograph The rule that settles half the exam questions: "-meter" measures, "-graph" records ALTIMETRY FOUNDATIONS Your altimeter is an aneroid barometer with a dial relabelled in feet It assumes ISA. The real day is never ISA. HEIGHT, ALTITUDE, ELEVATION, FLIGHT LEVEL — the vocabulary that must be exact THE FOUR PRESSURE SETTINGS Index, gravity and temperature corrections applied before any setting is issued QFE — zero on the runway. Height above the aerodrome. QNH — reduced to MSL assuming ISA. Reads aerodrome elevation on the ground. QFF — reduced using the ACTUAL temperature. Why forecasters use it for synoptic charts, and why pilots do not set it. QNE — 1013.25 hPa. Pressure altitude and Flight Levels. Hotter than ISA gives a QFF LOWER than QNH. At MSL the two are equal. Regional QNH — the forecast LOWEST pressure in the region, and why that is deliberately safe TRANSITION Transition Altitude, Transition Level, Transition Layer Down low use the LOCAL pressure so you agree with the GROUND. Up high use the SAME pressure so you agree with EACH OTHER. STANDARD ISOBARIC LEVELS 850 to 5,000 · 700 to 10,000 · 500 to 18,000 · 400 to 24,000 · 300 to 30,000 · 200 to 38,000 · 100 to 53,000 How to hold the table in three chunks instead of seven separate facts ═══ STILL TO COME ═══ Over-reading and under-reading (H-L-H and L-H-L) · "High to Low, look out below" · Alticor and D-value · Wind drift, altimeter error and Buys Ballot's Law · Semi-diurnal variation Recap of Parts 1 and 2 Pressure gradient The "iso-" family Contours and gpm Thickness Tendency and isallobars Barometers and barograph What your altimeter actually is Height, Altitude, Elevation, Flight Level QFE QNH QFF QNE and 1013.2 Regional QNH Transition Altitude and Level Standard isobaric levels Recap ═══ QUESTION BANK ═══ The question bank for this chapter is in a SEPARATE playlist. Every question is worked the same way — the correct answer, why it is correct, why each other option is wrong, and the concept it links back to. Notes first, then the QB. ═══ DISCLAIMER ═══ Feel free to share this. No terms, no conditions, nothing to sign. Aviation training in India needs to be decentralised, and that only happens if material moves freely. The YouTube channel Capt. Coalfield is no longer owned by Kumar. Uploads are made per Agreement GRN No. 2504039876. Please do not learn this by heart. Ask Why, ask What, ask How. And do not rely on AI alone — verify against your book and your instructor. Including this. ═══ LAST WORD ═══ Feedback and corrections: capt.coalfield@gmail.com Replies are slow. Digital detox is a real thing and I am bad at email. If this helped you, help someone else — a colleague, a friend, a stranger in the briefing room. I believe in karma. And spend time with the people who love you, your parents especially. The syllabus will still be here tomorrow. NOT FOR PROFIT — SLEEPY NOTES #DGCA #Altimetry #CPL #ATPL #QNH #Meteorology #AviationMeteorology #DGCAExam #PilotTraining #GroundSchool #SleepyNotes #CaptCoalfield #ICJoshi #AviationWeather #IndianAviation