The Importance of Density Altitude

Density Altitude:  Pressure Altitude corrected for non-standard temperature.

That’s the book definition of density altitude.  The problem is, that definition leaves a lot of general aviation pilots scratching their heads.  What really is density altitude?

All airplane engines rely on air and fuel mixing together, then that mixture is ignited to create combustion. Normally aspirated piston engine airplanes get their best performance at sea level, where the air is nice and thick, allowing plenty of air molecules to get sucked in the engine intake.  As a normally-aspirated airplane climbs, the ambient air pressure drops with an increase in altitude (the air gets thinner, less dense), thereby reducing airplane takeoff, climb, and landing performance.  There just isn’t as much air at higher altitudes, to put it simply.

Turbo charged piston engines assist with this air density problem.  A turbo charger boosts the air coming into the engine and fools the engine into thinking it is at sea level pressure all the time.  The higher the altitude, the faster the turbo charger spins, spinning the compressor faster, which compresses more air to continue to give the engine sea level pressure air.  This gets faster cruise speeds the higher you go.

Both normally aspirated & turbo charged engines do experience longer takeoff rolls and reduced climb rates at higher airport elevations & higher altitudes.

How does this all relate to density altitude?

When the outside air temperature rises, the air becomes thinner, less dense.  This means that when an airport elevation is 1,000 feet, but the density altitude is reported as 3,000 feet, the airplane engine thinks it is at 3,000 feet.  It won’t accelerate as fast.  The airplane’s climb rate will also be reduced.  That means that the normal climb pitch attitude a pilot is used to seeing won’t be accurate at higher density altitudes. It will lead to slower indicated airspeeds, slow enough to potentially lead to a stall if a pilot isn’t paying attention.

Where does this get dangerous?  High elevation airports.  Whenever the OAT creeps above 85 or 90 at an airport that is higher elevation (I would classify higher elevation as 2,500 feet or higher), the corresponding density altitude sky rockets.  If a pilot isn’t paying attention to airspeed or angle of attack (if the airplane is equipped with an AOA), a stall can come very quickly on climb out.

What to take home from this?  Monitor your climb speed and angle of attack, especially right after takeoff, when you hear density altitude on the ATIS or AWOS.

Similar Posts

  • Conroe, TX CPPP

    The Cirrus Pilot Proficiency Program (CPPP) will be coming to the Galaxy FBO at the Lone Star Executive Airport in Conroe, TX again this year.  The dates of the event will be October 14th-16th.

    Wondering what the CPPP program is?

    “CPPP offers a weekend event for Cirrus owners and their partners that focuses on Cirrus-specific knowledge and flying proficiency.  We bring some of the most experienced flight instructors who regularly teach in all kinds of Cirrus airplanes flown for all kinds of missions.  We have prepared an extensive syllabus of ground courses that complement the transition training and delve into areas of greatest need for Cirrus pilots.” (from CirrusPilots.org)

    CPPP

    The weekend starts off with a group dinner on Friday night. The Saturday morning ground session focuses on General Aviation Safety with special focus on the Cirrus accident statistics.  Normal and emergency procedures are also reviewed.

    In the afternoon on Saturday, the attendees are split into two groups.  The first group has a myriad of options for ground sessions covering all topics related to Cirrus aircraft and operations.  The second group flies, then they switch for the second 3 hour session.  Sunday brings the same split, with more courses offered and more flying.

    While the Cirrus pilots are flying and learning more about their airplanes, CPPP offers a Partner in Command course for flying partners on Saturday.  This allows flying partners to be more comfortable in the airplane and teaches them what to do if something were to happen to the pilot.

    All in all, attending a CPPP will improve both Cirrus knowledge and Cirrus flying skills.  It’s highly recommended for all Cirrus pilots.

    To register for the CPPP event in Conroe, check out the CPPP website.

    The Cirrus Pilot Proficiency Program (CPPP) will be coming to the Galaxy FBO at the Lone Star Executive Airport in Conroe, TX again this year.  The dates of the event will be October 14th-16th. Wondering what the CPPP program is? “CPPP offers a weekend event for Cirrus owners and their partners that focuses on Cirrus-specific…

  • Garmin VNV

    The Garmin G1000/Perspective combined with the Garmin GFC 700 Autopilot can be a great tool in descent planning.  When you want to end up at pattern altitude a certain distance from the airport or you get a clearance to cross a fix at a certain altitude, Garmin VNV is a great tool.  Here’s how to use it.

    VFR Garmin VNV Use

    Let’s say you want to end up at pattern altitude 3nm from your destination, but you don’t want to descend down into the bumps before you have to.  Here’s how to set it up:

    • Go to the Flight Plan page on the MFD
    • Press the ATK OFST soft key on the bottom of the MFD.  It stands for Along Track Offset, which, in laymen’s terms, means you are setting a point along your track a certain distance from your destination.  In this case, it will be 3nm
    • Input the distance using either the keypad or the small FMS knob and press enter
    • Select the altitude you want to be at (in this case pattern altitude) and press enter
    • You will see a point 3nm before you destination appear on your magenta line and a Top Of Descent (TOD) appear where you need to start your descent
    • 1 minute before the Top Of Descent, an indicator will appear next to your altimeter
    • To have the GFC 700 Autopilot fly the descent for you, you have to do two things
      • Set the Altitude bug for the desired altitude
      • Press VNV on the autopilot
    • All you have to do now is manage power

    IFR Garmin VNV Use

    Let’s say you are told to cross a fix at a specific altitude.  Here’s how to use Garmin VNV to plan it out.

    • Go to the Flight Plan page on the MFD
    • Turn the cursor on and highlight the altitude blank next to the fix in the flight plan
    • Input the desired altitude
    • You will see a Top Of Descent (TOD) point appear along your course where you need to start your descent
    • 1 minute before the Top Of Descent, an indicator will appear next to your altimeter
    • To have the GFC 700 Autopilot fly the descent for you, you have to do two things
      • Set the Altitude bug for the desired altitude
      • Press VNV on the autopilot
    • All you have to do now is manage power

    The Garmin G1000/Perspective combined with the Garmin GFC 700 Autopilot can be a great tool in descent planning.  When you want to end up at pattern altitude a certain distance from the airport or you get a clearance to cross a fix at a certain altitude, Garmin VNV is a great tool.  Here’s how to…

  • Santa Fe Fly In Canceled

    Sadly, Texas Top Aviation is having to cancel it’s 2020 Santa Fe Fly In due to COVID. New Mexico has continued to implement travel restrictions, making it difficult for Texas Top Aviation to complete the event.

    Mark your calendars now, though, as Texas Top Aviation has scheduled is 2021 Fly In. We are returning to the Lajitas Golf Resort in the Big Bend area of Texas. The event will be March 24th-26th, 2021. Stay tuned for more information. We hope to see you there!

    Sadly, Texas Top Aviation is having to cancel it’s 2020 Santa Fe Fly In due to COVID. New Mexico has continued to implement travel restrictions, making it difficult for Texas Top Aviation to complete the event. Mark your calendars now, though, as Texas Top Aviation has scheduled is 2021 Fly In. We are returning to…

  • What’s Going On With the Airplane Market?

    An Airplane Market Update, Q2 2026

    I get asked some version of the same question almost every day right now: “Hank, what’s going on with the airplane market?” Owners are nervous. The market has definitely slowed down, and the second quarter has been especially quiet. So let me give you a straight read on what’s actually happening, why, and what it means for your airplane.

    Here’s the short version: don’t panic. A slow market is not a market crash. It’s a market that rewards sellers who price realistically and buyers who are ready to pull the trigger. Patience is the name of the game right now.

    PDF
    ★ Free Download
    Get the Full Q2 2026 Aircraft Market Report
    The complete write-up — values, trends, and forecasts broken down by airframe. Sent straight to your inbox, free.

    Where values have actually been heading

    Used airplane values shot up through the COVID years, peaked somewhere around 2022, and have been softening ever since — really since about 2023. That’s carried into 2026. But in most piston airplanes, it looks a whole lot more like a slow, steady give-back than a crash.

    Now, here’s where I’d rather look than at asking prices. An asking price is just what a seller is hoping — or dreaming — to get; it isn’t what the airplane is worth. What an airplane is actually worth is what VREF tracks. And when I pull the VREF values on the single-engine pistons I’ve been appraising lately, a clear pattern shows up:

    • Older and less expensive airplanes are holding up the best. A clean normally-aspirated G1, G2, or G3 Cirrus SR20 or SR22 is down about 3% over the last twelve months. Older, more classic airplanes — Bonanzas, a Cherokee Six, a clean P210 — are flat to down just a few points. One outlier is the Cessna/Columbia 400 market — those are down about 13%.
    • The newer and more expensive, cabin-class singles have dropped more. A pressurized Malibu Mirage is down around 12% on VREF value, with other PA-46 pistons and turbines valued a little better, but still down between 8–12% over the last year.

    Call it roughly 5% on average across the segment. That’s more than the under-1% you’d guess from asking prices alone — but it’s still less than 15% down over the last year, not a crash. The rule of thumb: the older and less expensive the aircraft, the better the values are holding; the newer and more expensive the aircraft, the more the value has dropped over the last year.

    What a Crash Actually Looks Like

    Worth being precise about what I mean. A real crash — like 2008–09 — is sudden and disorderly: values plunge almost overnight, financing dries up, buyers walk away from their deposits, and airplanes sit because there’s no one to buy them at any price. New business-jet deliveries fell nearly 34% in a single year, and it took years to climb back. What we have now is the opposite on every count — value drops of 15% or less, financing that’s tighter but still available, and airplanes that are still changing hands. That’s a soft, orderly market, not a crash.

    Why Q2 got so quiet

    A handful of things piled up at the same time. None of them is a disaster on its own, but together they explain why the phone has been ringing less.

    Rates didn’t come down the way everybody expected. Oil shot past $110 a barrel after the conflict with Iran, inflation came roaring back, and the Fed stopped dropping rates — so financing an airplane still costs more, and that takes the urgency out of buyers. Financing also got tighter; the days of 100% loans with no money down are basically over, and lenders want bigger down payments.

    The tax rush already happened, too: when the One Big Beautiful Bill brought back 100% bonus depreciation, it set off a mad dash to close before year-end, and a lot of the folks who’d have been shopping this spring already bought last winter. Plus, there are simply more airplanes to choose from now, which hands buyers options and pulls pricing power away from sellers.

    So what should you do?

    It depends on which side of the deal you’re on.

    If you’re selling, price to today’s market — not the 2022 peak, and, unfortunately, not what you paid for the airplane. Realistically priced airplanes are still selling; the ones that sit are the ones chasing a number the market left behind. Keep your logs complete, stay current on inspections (don’t forget those 24-month IFR inspections!) and ADs, and present the airplane well. Have a thorough annual done before putting it on the market. Keep it clean and do whatever cosmetic or avionics fixes or upgrades you’ve been neglecting — you want it to show as well as possible, because there’s a lot of competition out there.

    Re-dyeing the leather seats is a cost-effective way to spruce up the interior without replacing the seats. A good wash will certainly help the exterior. Glass in the panel always shows better than steam gauges, so even something simple like an Aspen upgrade, two Garmin GI 275s or G5s, or a 7-inch Garmin G3X will bring value to your airplane and make it show better — any of those are less than $10,000. If you do still have a Garmin 530W or 430W, consider changing them out for a newer Garmin or Avidyne IFD unit; Garmin won’t support the 530W/430W anymore. And Avidyne is quietly ending support for the Entegra system this fall — but the good news is the Avidyne Vantage panels are finally certified.

    And if you can wait, give it some thought — the back half of the year is shaping up stronger. The fourth quarter is traditionally the best stretch for used sales, and now that bonus depreciation is permanent, that year-end push resets every fall.

    If you’re buying, this is your window. Higher rates have thinned out the competition, there are more airplanes to pick from than there have been in years, and sellers are more willing to deal. If you’ve got cash ready or financing lined up, you’ve got leverage you didn’t have eighteen months ago. Be picky — buy the clean one with good records.

    If you’re just holding, relax. There’s no reason to panic-sell. Most piston values are easing off slowly, not collapsing. Patience wins here.

    The right move always comes down to your specific airplane, your timeline, and what you’re trying to accomplish. If you’d like a current valuation — or just an honest read on where your airplane sits in today’s market — give me a call. That’s what we’re here for.

    An Airplane Market Update, Q2 2026 I get asked some version of the same question almost every day right now: “Hank, what’s going on with the airplane market?” Owners are nervous. The market has definitely slowed down, and the second quarter has been especially quiet. So let me give you a straight read on what’s […]

  • Cessna TTx Production Ceases

    Sadly, in January, a pretty great airplane was put out to pasture.  Textron (the conglomerate that now owns Cessna, Beechcraft, Hawker, and Lycoming) announced it was ceasing production of the Cessna TTx.  With the end of the Cessna TTx production, an airplane that was the main “competitor” to Cirrus (if you can call it competition; Cirrus consistently outsold the Cessna TTx by a wide margin each year), it leaves the SR series to stand alone atop the High Performance piston single market.

    I got to go through Cessna’s FITS Accepted Instructor (CFAI) course back in 2012 and have flown in the Cessna 350 and 400 (which is what they were known as at the time; the Cessna TTx name came around in 2011) for about 120 hours.  I really like the airplanes.  I’m partial to the Cirrus, but the Cessna 350 & 400 are fast airplanes and great for 1-2 people.  I flew a 350 (the non-turbo charged version) from New York to San Antonio last fall and routinely saw 170 knots at 12 GPH.

    Columbia started out making the 350 & 400 (the turbo-charged version) in the early 2000s, but went bankrupt in 2007.  Lancair started Columbia to make a certified version of their popular kit planes.  If you see a Lancair ES floating around, you would swear it’s a Columbia with only 1 door.  Cessna bought the design from Columbia in 2007 to begin manufacturing the airplanes themselves.

    Cessna then made a huge mistake as they moved the production facility from Bend, Oregon to Mexico. Production completely halted in 2009 as the planes coming out of Mexico were found to have defective composite work.  The sales never really recovered, even though Cessna put the Garmin G2000 panel in the Cessna TTx, complete with a touchscreen key pad.  A FIKI system was added as an option in 2012.

    A prospective buyer can still get a great value on a used 350, 400, or TTx, as they are valued a little lower than a Cirrus.  The 350, 400 or TTx all make excellent single pilot or two person speedsters with very comfortable amenities.

    Information for this article was taken from Flying Magazine’s website.

    Sadly, in January, a pretty great airplane was put out to pasture.  Textron (the conglomerate that now owns Cessna, Beechcraft, Hawker, and Lycoming) announced it was ceasing production of the Cessna TTx.  With the end of the Cessna TTx production, an airplane that was the main “competitor” to Cirrus (if you can call it competition;…

  • Night Flying Techniques

    We’ve all been there. You’re flying into an unfamiliar airport at night, you’re having difficulty seeing the field, and trouble identifying the runway. Airports can be hard to identify for a variety of reasons, but approaching in darkness only makes it more difficult. Perhaps the airport is located in a densely populated area and the airport lights bleed into the city lights. Maybe the airport that you’re approaching is located amid terrain that obstructs your view.

    Situations like these are not uncommon for charter pilots. Just a few evenings ago I was descending IFR into Asheville, NC (KAVL) on a dark night with high overcast and scattered showers. Although the airport was VFR, the surrounding hills made me doubtful that I would be able to see the field in time to safely and comfortably descend for the visual approach that I was expecting.

    Fortunately, there are some things we can do to help find our destination and set us up for the approach. Here are a few tricks that I use regularly when I find myself in this position:

    • When flying into an untowered/closed tower airport: Make sure that you have the right lighting frequency. Some airports have pilot-controlled lighting that is operated on a different frequency than the CTAF. If the lights don’t seem to be working, consult your AFD. If the AFD advises that your frequency is correct, double check the NOTAMs to make sure that the lights haven’t been taken out of service.
      • For towered airports: Ask the tower controller to turn up the intensity of the runway lights. This has helped me find the runway countless times. This request can be especially useful at airports that are located in a highly lit area. Controllers are happy to honor this request and will often leave the lights at the bright setting until you advise them that you are ready for them to be turned back to normal intensity.
    • Load an approach: If you are an instrument rated pilot, loading an instrument approach is a great way to get oriented with a runway when you need a little help. You may need to coordinate with the tower or controlling agency if you want to fly the approach, but this has the added bonus of giving the pilot altitudes for terrain/obstacle clearance should there be any hazards present.
    • Use OBS mode: If you are flying an airplane that has equipment capable of doing so, you can use the Omni Bearing Selector (OBS) button to help align you with the runway. If using this strategy, just remember: THIS IS NOT AN INSTRUMENT APPROACH. It will not provide you with obstacle clearance, nor will it line you up directly with the runway.

    The pictures below should help clarify how to use the OBS to assist in airport orientation.

    Step 1- Have the destination set as the next way point in your flight plan. In the picture below, The GPS is set to navigate direct to KJGG. Press the OBS button (circled in red) to engage the OBS mode.

    OBS 1

    Step 2- Once OBS is selected, use either the window on the screen (which should come up automatically when you press the button in step 1) or the OBS selec tor on your navigation head to select the inbound radial. In this example, I have selected 310 degrees, the landing runway at KJGG.

    OBS 2

    Step 3- The GPS now shows an inbound course to the airport of 310 degrees. It appears as a magenta line. The line serves as an excellent aid in airport/ runway orientation. Remember that this will not line you up perfectly with the runway, but it can still be extremely useful in planning a pattern entry or for getting your bearings.

    OBS 3

    Note: As shown below, If you press the OBS button again, the GPS will return to the navigation as previously set.

    OBS 4
    1. Ask for vectors to the airport/ runway: If you have VFR flight following or are talking to a tower equipped to provide vectors, asking for them can be a good choice. Although the controllers may not always be able to accommodate your request due to workload or equipment limitations, most will be happy to comply if they are able. Some pilots may feel silly asking for help, but my policy has always been that I’d rather feel silly for asking than look silly for being lost.

    In the case of the Asheville flight mentioned in the opening of this article, my solution was to ask the controller fo r direct to the final approach fix of the assigned runway. Upon arriving there, I had no trouble seeing the VASI and was in good position to fly the visual approach. If I had wanted to be positioned a little further out, I could have asked to fly to a different fix or simply asked to be cleared for the approach in lieu of the visual. Just remember to keep your intentions clear when communicating them to the controller.

    The best way to approach an airport day or night, familiar or unfamiliar, is with careful preparation. Having lighted landmarks picked out as well as being acquainted with the airport layout will pay off when it comes time to plan your pattern entry or find the airport on a dark night. Use the resources available to you to get you safely to your destination.

    Andrew Robinson is a 135 Charter Pilot and flight instructor in Pennsylvania.  He flies Pilatus PC-12s and instructs in Beechcraft Bonanzas.

    We’ve all been there. You’re flying into an unfamiliar airport at night, you’re having difficulty seeing the field, and trouble identifying the runway. Airports can be hard to identify for a variety of reasons, but approaching in darkness only makes it more difficult. Perhaps the airport is located in a densely populated area and the…

Leave a Reply

Your email address will not be published. Required fields are marked *