QNH and altimeter settings help Skywest ERJ pilots read altitude accurately and fly with confidence.

Outline (skeleton)

• Opening note: QNH as a practical, everyday factor in the cockpit

• Section 1 — What QNH is: the atmospheric pressure adjusted to sea level for altimeter settings; how it differs from QFE and QNE

• Section 2 — Why it matters: altitude accuracy, terrain and traffic separation, weather effects on pressure

• Section 3 — How pilots use QNH: setting the altimeter on the ground, during climb, cruise, and approach

• Section 4 — A real-world mental model: picturing QNH in flight planning and operations

• Section 5 — Quick practical tips for SkyWest ERJ crews and KV/QK knowledge

• Closing thought: keep the number in your mental toolbox

QNH in the SkyWest cockpit: what it is and why it matters

Here’s the thing about QNH. It's not just another line on a weather chart or a trivia fact tucked away in the flight manual. QNH is the atmospheric pressure adjusted to sea level that pilots dial into the altimeter to read true altitude above mean sea level. In plain terms, it’s the value that makes your altimeter tell you how high you really are above the ground at sea level, not just above the air pressure at your current location. For SkyWest ERJ crews and any crew flying in varied weather and terrain, that number matters more than you might think.

Let’s unpack the label a bit. QNH isn’t a type of navigation system, nor is it a cruising speed or a set altitude. It’s a pressure value. Air pressure at the surface changes with weather—neat winds, low-pressure systems, high-pressure ridges. When you take a measurement at a specific airport, you’re capturing the local pressure, then warped up or down to sea level to create the QNH. Setting that value in the altimeter aligns the instrument with the actual altitude above sea level at your destination and along your route. It’s a small dial, but it has big consequences.

If you’ve flown close to mountains or coastal airports, you’ve probably felt how pressure changes can nudge your readings. Mild weather shifts can tilt your altitude by a few hundred feet. That’s exactly why QNH is treated as a core tool in flight planning and in-the-cockpit operation. When the aircraft sits on the ground, the altimeter should read the field elevation if the QNH is set correctly. If you land at one field and depart from another with a different QNH, your altimeter will not magically match the ground unless you adjust it. That is the practical difference between safe altitude awareness and a misread that could put you in closer proximity to terrain or other traffic.

QNH versus other pressure settings: the quick distinction

A lot of pilots talk about QNH, QFE, and QNE in the same breath, which can be a little confusing at first glance. Here’s a simple way to keep them straight:

• QNH: pressure reduced to sea level for standard altimeter settings. This is about altitude above mean sea level. It’s what you use for most en-route and approach work in non-hemispheric transfer airspace.

• QFE: pressure at the airfield, as read at the airfield elevation. Setting QFE makes the altimeter read field elevation when you’re on the ground. It’s handy for quick cross-checks at a known airport, but not typical for cruise or approach planning across a region.

• QNE: the standard pressure setting, 1013.25 hPa (or 29.92 inHg), used when flying at or above the standard altitude layer, regardless of local pressure. It helps keep jet streams and high-altitude traffic consistent when weather changes are fast and weather systems move.

Bottom line: QNH is about altitude above sea level, corrected for local weather. QFE is about the elevation of the airport itself. QNE is the standard pressure used at higher flight levels. Each serves a purpose, and knowing the distinction helps keep both your situational awareness and your instrumentation clean.

Why QNH matters in real life

Altitude accuracy isn’t a nice-to-have; it’s a safety thing. If your altimeter isn’t correctly set, you could end up either too high or too low for the airspace you’re in. That affects obstacle clearance, terrain avoidance, and traffic separation. In busy airspace, especially around airports with rising mountains or sea cliffs nearby, a few hundred feet can be the difference between a clean flight path and a near-miss scenario.

For the ERJ pilots at SkyWest, you’re juggling short legs, tight approach slots, and weather that loves to throw little pressure quirks your way. A change in weather can tilt the local pressure, which shifts your true altitude if the altimeter isn’t updated. Remember, the altimeter is your primary instrument for height. If you’re climbing through layered clouds, descending into fog, or lining up for an instrument approach, you want that altitude readout to reflect the actual height above mean sea level. That’s what keeps your vertical separation from terrain and other aircraft honest.

A practical mental model helps a lot. Think of QNH as the “zero” reference for your altitude when you’re at sea level pressure. You adjust the altimeter to that reference so the instrument shows you your real height above sea level. If the pressure field around you drops because a weather front rolled in, your QNH helps you re-zero, so your altitude reading tracks your actual height more faithfully as you move with the air mass. In other words, QNH ties the cockpit to the ground you’re over, even as you’re up and moving through the sky.

How pilots actually use QNH in flight

In the cockpit, the process is straightforward but crucial. After engine start and before takeoff, the crew sets the altimeter with the local QNH value. This value comes from weather services, METAR reports, or tower/unicom broadcasts at the airfield. On departure, you’ll often see the QNH posted in the ATIS, on the tower frequency, or in the flight information region’s weather menu. The moment you go through the pre-takeoff checks, you dial in that QNH so the altimeter reads the field elevation when you’re taxiing, and then climbs are tracked against a corrected altitude reading.

As you move away from the field, the pressure you’re truly dealing with changes with the weather system around you. That’s why you’ll hear or read about updating QNH in certain flight phases or for specific routes, especially when crossing airspace with multiple weather stations. The key is consistency: keep the altimeter set to the latest local QNH whenever practical, and be mindful if you’re transitioning between airports with notably different pressure readings.

Approach, landing, and the safety net

Approaches are where the rubber meets the runway in many ways. If your altimeter is off by even a couple of hundred feet, you could miss the decision altitude or misjudge the glide slope. In landing configurations, you want your vertical profile to line up with the certified approach path. QNH helps ensure that your altitude readout corresponds to your actual height above the runway elevation at the destination, which makes landings smoother and safer.

It’s not just about the numbers, either. QNH also interacts with performance calculations, like how much vertical descent you need for a stabilized approach, how much fuel is left, and how you’ll manage air traffic flow around a busy terminal. When you factor in crosswinds, turbulence, and weather, the faithful application of QNH becomes a small daily discipline that pays off in reliability and calm in the cockpit.

A quick mental model you can keep handy

Here’s a simple way to visualize QNH in action. Picture the air around you as a big field with invisible pressure lines. The value you set is like turning a dial that snaps those lines to zero at sea level. If the field changes pressure—say, a weather front sweeps through—that dial re-zeros to keep your altitude reading honest relative to sea level. In practice, you’re not just watching a number; you’re watching your height above terrain and water, especially when you’re near coastlines or towering features.

Small reminders in daily flight life

• Always check the latest QNH for the airfield you’re at and the field you’re approaching. Weather changes quickly; old numbers aren’t trustworthy for new legs.

• If you’re transitioning between airports with different elevations and weather pressures, refresh your QNH at the new field to keep altitude readings consistent.

• Use the altimeter as your primary height reference, but cross-check with radar altimeter (where applicable) and vertical navigation data when you’re in instrument conditions.

Practical notes for SkyWest ERJ crews and KV knowledge

For those studying the knowledge side of the job, remember the core fact: QNH is the atmospheric pressure adjusted to sea level for altimeter settings. This single line anchors a lot of cockpit reality. The following points tend to come up in day-to-day operations and the kind of knowledge that helps you sound confident in the cockpit or in a write-up:

• Ground truth: When you’re on the ground, a properly set QNH should make the altimeter read the field elevation. It’s a useful cross-check that your instrument is in good shape.

• Weather-driven shifts: Local pressure varies with weather. The QNH provides the bridge between a local pressure reading and accurate altitude above mean sea level as you move around in the system.

• Altimeter discipline: The altimeter is a safety instrument. Keeping it properly set reduces the risk of altitude errors during climbs, cruises, and approaches.

If you’re curious about the bigger picture, you’ll notice this concept threads through many en-route decisions. It connects to how you plan flight levels, how you interpret METARs and TAFs, and how you coordinate with air traffic control when weather is changing faster than the timetable.

A note on tone and purpose

This article is meant to demystify QNH, not overwhelm you with jargon. It’s about seeing a single number as a practical tool that keeps you aligned with the ground beneath and the sky above. The goal isn’t to memorize a line item for a test—though obviously you’ll want to know it well—but to understand how that line translates into safe, predictable flight behavior.

Closing thought

QNH isn’t glamorous, and that’s precisely why it’s so important. It’s the quiet, steady companion that helps you stay level in a world of shifting pressure and changing skies. When you dial in the local QNH, you’re doing more than setting a number. You’re anchoring your altitude, safeguarding your separation from terrain and other traffic, and making the whole flight pattern a little more predictable for everyone onboard.

If you walk away with one takeaway, let it be this: QNH is the atmospheric pressure adjusted to sea level for altimeter settings, and it’s your ally in keeping height honest—whether you’re cruising over prairie land, skirting coastal lines, or lining up for a precise approach at a busy airport.