Pre-buy Validation Flight

I've done this a few times and while you could liken the process of buying an airplane to that of buying a luxury automobile, it is quite a bit more complicated. Like buying a car, you really ought to "test drive" the airplane before agreeing to sign on the bottom line. The seller will probably limit you to one flight and that flight could be as short as a few hours. That isn't a lot of time and your should have a good idea of what you want to check. I have a short, generic checklist for you, as a starting point. You will need to tailor it to fit the aircraft type and the specifics of your operation. Make sure you pass this around the flight department; you will be surprised at how much the team can contribute.

Most of my aircraft purchasing experience is with Gulfstreams, so there are a few items that apply to Gulfstreams that may or may not apply to your situation. But the overall checklist can be adapted for any airplane.

Before the flight: paperwork

Make sure the aircraft logs are complete, reflecting total airframe, engine, and APU times. Sample past paperwork for the presence of aircrew write ups, deferred maintenance, and correct return to service entries. An absence of any of these might mean some maintenance has been undocumented and perhaps not “by the book.”

Before and during the flight: cabin

Inspect the cabin, interior, galley, and lavatory systems for presentation and functionality. Make sure all drawers, tables, doors, shades, lighting, phones, A/V equipment etc. function as they should. It may be helpful to bring a thermometer to check refrigerators and ovens. Bring along a microwave-safe container to test the microwave by attempting to boil water.

Before the flight: cockpit

Look for missing panels, worn labels, and non-standard items. Older aircraft may have a wide variety of cockpit layouts while newer aircraft tend to be more standardized. The wear and comfort of seats and armrests should be noted. Move seats to their location limits, including recline if available. Test all lap and shoulder harnesses. Deploy oxygen masks and test according to the AFM.

Before and after the flight: computerized maintenance systems

Examine active and stored faults in the Central Maintenance Computer (or equivalent) to examine the normal operation of the aircraft and expose things that may not be "normal", but can be somewhat embedded.

Exterior Inspection

Complete the exterior inspection with a copy of the AFM procedure in hand. Look for fluids in excess of normal drip or seepage allowances. Look for dirty landing gear struts which could indicate the aircraft’s maintenance has been sub par. Examine the paint thickness; if you can see metal through the paint it may be overdue a repaint. Check that all required covers are available. Check all windows, cabin and cockpit, for cracks, crazing, or discoloration. Look for dents and cracks on all surfaces. Check the tires for wear, cut marks, and tread integrity. Check the brake wear pins (if present) and look for caked on brake dust.

Cockpit Preflight Check

Have the flight crew follow the AFM procedure exactly, including all first flight of the day checks and others which might not be required on every flight. Any failed items need further investigation. Listen for abnormal noises or the absence of normal clicks and other sounds. Note the boot up time of systems, most notably displays.

Flight Check: Methodology

It would be useful to get the aircraft up to altitude as soon as possible to get the aircraft as cold as possible to test form, fit, and function of various cockpit and cabin systems when cold soaked. Having one of your pilot’s flying the aircraft and another pilot on the jump seat to take notes and other observations is very useful. Having a mechanic and flight attendant in the cabin is also helpful. On return, an instrument approach to a go around and another approach to landing can also prove useful.

Throughout the flight, make sure knobs, switches, avionics, and other systems function as they should. Listen for odd noises, rattles, squeaks, and thumps.

Flight Check: Engine Performance

• Monitor startup time and smoothness (look for unusual noises or excessive smoke).
• Check for proper thrust response and symmetry between engines.
• Observe fuel consumption and engine temperature trends (should be within limits).
• Watch for vibration or unusual engine behavior.

Flight Check: Avionics & Instrumentation

• Ensure all avionics systems function properly (FMS, autopilot, TCAS, radar, ADS-B, etc.).
• Check for GPS accuracy and navigation system performance.
• Test the autopilot and flight director modes in various conditions.

Flight Check: Pressurization

• Evaluate pressurization system functionality (cabin altitude vs. actual altitude). If time permits, bring aircraft to maximum altitude and note cabin altitude and differential pressure. Listen for sounds of air leaks (usually a whistling noise) throughout the cabin.
• During climb and descent, note any abrupt pressure changes, usually felt in your ears.

Flight Check: Handling & Flight Control Response

• Confirm stability and trim at different speeds and configurations. Hand fly the aircraft, trim, and release the controls to confirm the aircraft will hold its attitude.
• Test control inputs (rudder, ailerons, elevators) for smooth operation.
• Simulate a go-around procedure to test responsiveness.

Flight Check: Electrical & Hydraulic Systems

• Examine circuit breaker panels and other electrical panels for signs of excessive wear, burning, or frequent replacement.
• Ensure hydraulic pressure and fluid levels remain stable by making note of levels before and after the flight.
• Test flaps, gear operation, and speed brakes.

Flight Check: Landing Gear & Brakes

• Verify gear extension/retraction smoothness.
• Look for gear warning lights or unusual noises.
• Test anti-skid braking and ensure no excessive brake fade.
• Examine wheels and brakes after the flight to see if they have becoming abnormally hot, given the demands of the flight.

Flight Check: Environmental Systems

• Test heating and air conditioning system responsiveness to changes from cockpit and cabin control systems, look for odd smells and air particles.
• Monitor cabin pressurization and oxygen levels.

Flight Check: Noise & Vibration

• Note any excessive vibrations or abnormal noises in different flight phases.
• Check for wind noise and cabin insulation quality.
• Have someone sit over the landing gear during taxi, takeoff, gear and flap retraction, gear and flap extension, landing, and braking. Unusual sounds and vibration may indicate structural issues.

Flight Check: Communication Systems

• Ensure VHF/HF radios work properly.
• Test intercom and SATCOM systems if installed.
• Test datalink with a PDC where available.

Flight Check: Autoland & Auto-brake (if applicable)

• Test auto-brake performance and verify smooth deceleration and achieved distance versus AFM.
• Check autoland capability.

Flight Check: Emergency Systems

• Test emergency lighting.
• If time permits, check cabin oxygen mask deployment.
• Check inspection dates and condition of all oxygen masks, fire suppression systems, fire extinguishers, life vests, and life rafts.
• Ensure backup instruments function properly.

Post-Flight Review

• Check the aircraft logs for any anomalies or warnings.
• Review fuel burn efficiency.
• Check end fluid levels versus starting levels.

Items not checked

Make note of critical items you were unable to check, such as data link systems or autoland capability. Consider adding a clause to any purchase agreement that these items will be tested after delivery and agree on a timeline for test and repair.

One of my jobs at the Pentagon was buying aircraft for the Air Force and I reprised that role a few times as a civilian. Of course, I also bought many cars over the years. With the exception of dealing with Tesla, where no salesperson was involved, every purchase seemed to be adversarial. The seller wants as high a price as possible, you want the opposite. But the worst part of the transaction is the "bending" on truth from the seller. Perhaps a short story is in order.

The Challenger was originally built by Canadair (now Bombardier) and was called "Challenger," I've been told, because it would challenge the Gulfstream GIII and later the GIV. Spoiler alert: the challenge failed. While I was at the Pentagon, I bought a couple of Gulfstream GIVs but had to entertain offers from the competition. Only Canadair offered an alternative choice. The company brought in a Challenger 601 for me to fly with the soon-to-come Challenger 604 in mind. Our acquisition criteria specified a business jet that could fly twelve passengers from Washington, D.C. to Frankfurt, Germany, non-stop, something the GIV could do. Canadair said they could do that.

The Canadair sales pilot was a former Air Force One pilot from Andrews, where I was assigned prior to the Pentagon. He was friendly enough and gave me a free hand with the aircraft. The aircraft felt very small to me. It was, in fact, the smallest jet I had ever flown since Air Force pilot training. "This thing can make DC to Frankfurt on one tank of gas?" I asked. "Sure can," he answered. As I left the aircraft I asked, "Twelve pax?" "Yup."

It just didn't make sense. On my drive back to the Pentagon I figured it out. I pulled over, found a pay phone, and called. "Will the Challenger 604 fly from D.C. to Frankfurt with twelve passengers on one tank of gas?" There was a long pause. "Well, not actually. It can make the hop, but not with twelve passengers." "How many passengers, then?" There was another awkward pause. "Zero."

That was a valuable lesson. You have to carefully construct the question to get the answer. The salesman may know the intent of your question, but will do his or her best to give you the answer you want, even if it isn't technically true. You may have heard the phrase,

caveat emptor

Let the buyer beware, which implies the buyer is at the seller's mercy. But that isn't completely true when buying an airplane.

Caveat venditor

Let the seller beware, means there is an implied warranty. At the very least, the seller implies the aircraft is airworthy. Unless the sales agreement says, "as is," or words to that effect, the buyer does have some protection. It pays to have a legal team with experience in aircraft purchasing. Give them a look at your checklist before the flight.