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Almost every pilot knows a GUMPS check is crucial. We run this mental checklist before we hit the Final Approach Fix or abeam the numbers in the pattern.
A GUMPS check is typically used to confirm that your aircraft has transitioned from an en route profile to a landing and go-around profile.
GUMPS is the acronym for Gas Undercarriage Mixture Pumps and Switches. And it is not just a landing checklist, it’s also a go-around checklist. While it should never replace an approved checklist, it is an effective supplement. It is even discussed in the AIM.
As a private pilot, you’re used to checking the fuel selector, setting the mixture to rich, and attending to switches, seatbelts, and such before landing. A GUMPS check takes it up a notch by adding gear and props. Why you should do it and how to do it well will be our focus today.
As an experienced corporate pilot, I can’t stress the importance of a GUMPS check enough. I’ve seen seasoned pilots forgo GUMPS and get to short final with their gear still in the well. They eventually realized and nothing bad happened, but if they hadn’t they risked their own lives, as well as those of everyone else onboard!
What Really is a GUMPS check?
A GUMPS check is a mental checklist of the critical matters that need your attention before you touch down. The approach phase of a flight is the busiest of all phases, and it is easy to skip something on the checklist.
For this reason, a GUMPS check comes in handy and makes sure that you are properly set up before you are on final.
G for Gas
The G in GUMPS check references gas.
Picture this. It’s the end of the flight, and the fuel in your tanks is not as much as it had been. If you had been switching tanks throughout your flight, it is likely that the selector is either set to the left or the right tank.
In the touchdown flare, your nose-high attitude could cause temporary starvation of fuel as the fuel sloshes to the back of the tanks. This could cause a sudden sputter just as you cross the threshold, close to being behind the power curve.
Or if you are coming in on a crosswind landing and you are pulling fuel from the lower wing, there is going to be a good chance that the engine is starved of fuel.
By checking your gas, and setting it to both tanks, or what is prescribed by the Operating Manual, you make sure that you have fuel from both tanks feeding the engine(s).
U for Undercarriage
In a complex aircraft, you have to think about the undercarriage. A gear-up landing is a quick way to lose your ticket while severely endangering the life of your passengers and crew.
When you do your GUMPS check, it is likely you’ve already lowered the gear during your pre-landing checklist. You also probably verified three in the green, heard the wheels knock the airframe as they extended into place, and felt the aerodynamics of the aircraft change.
So why check it again?
Simple. Gear mechanisms are complex and there are times that they don’t lock into place properly. They may indicate green when you first throw the handle, but as you make your turns, the gear may come unseated from its locked position. I have had this happen a couple of times.
If you don’t verify that you have three in the green during your GUMPS check, you could miss one or more lights that have switched to red. And there is no way to prove to the investigators that you saw three in the green before committing to your landing.
M for Mixture
Mixture settings depend on several factors. High density altitude landings require a leaner setting, while low density altitudes require a richer one. Check your Operating Manual.
For smaller aircraft, it’s almost always going to be set to rich when landing.
When you adjust your mixture lever, remember that the point is to get the right mix of fuel and air into your engine so that you burn what you need. Too rich, and your engine cools down so much that it’s not producing as much power as it could.
Too lean, and it runs hot, enough to cause a misfire and diminish your power output as you climb out.
Think about your mixture setting in the event of a go-around or a missed approach. If your missed approach requires you to do a power take-off at a steep angle from a high-altitude airport, then set the mixture setting for high power.
But if you are close to sea level, then you want your mixture set to rich, so that you will have all the power you need without the risk of overheating the engine on a go-around.
P for Props and Pumps
P has a couple of items that you need to remember. Set your props forward. It’s the least amount of drag imposed on your engine by the props. Think back to what your props are doing when you push the lever forward. It reduces the angle of attack for the prop and therefore the stress on the engine in the event of a go-around.
If your prop levers are set aft, then your high angle of attack during landing, and on take off, results in lower thrust on the descending side of the prop disc. This means you have low total thrust just when you need it most.
The P in a GUMPS check also references the fuel pumps. You need pumps on so that positive fuel pressure is maintained from all the tanks. Wind sheer, crosswinds, low fuel conditions, and the possibility of a clog from contamination, might cause the engine to sputter if left on just a gravity feed.
A fuel pump ensures that fuel is constantly being pushed to the system, and therefore reduces the risk of power loss on short final or upon a sudden power up on go around.
S for Switches, Seatbelts, and Safety
'Switches' is simple. It just means you need to turn on whatever needs to be turned on. This usually means things like lights and pitot heat.
Then it's time to get everyone to make sure they have their seatbelts and harnesses on.
Finally, a quick check of the safety concerns. Most importantly, you should brief your passengers that this is the point that they should refrain from talking. You should declare a sterile cockpit at this point.
That covers the what and the why. Now we come to the how.
How to Streamline Your GUMPS Check
The whole idea of the GUMPS check is to accomplish critical tasks that come about at a busy time and not be distracting while you navigate the terminal area. In the early days of my flying, I’d sit in the cockpit and close my eyes and move my hands from one lever or switch to the next as I did my dry run GUMPS check.
It usually flows very well. Using your right hand, when you start with the tank selectors they are usually just behind the pilots’ seats. With my eyes still on the instruments, or outside, my hands feel for the position and make sure that it's set to where I want it to be. Usually on both.
From there, it's just a straight swing up to the console. My eyes and ears are still focusing on the outside of the airplane while my hands find the landing gear knob. This is a two-step process. My hands verify it's in the down position, and my eyes leave the instrument panel to look at the three green lights.
My hand then falls to the power console. Before I move anything, I look over to check if my mixture is rich. If it's not, I advance the lever forward. And move right over to the props. In some aircraft, these are reversed. Advance the props at this point.
Setting the power should be to specifications for your final approach. Your aircraft should already be very close to your approach configuration at this point.
The next P in the GUMPS check is the pump. Depending on where your pump switch is, move your hand there while keeping your eyes on the aircraft, then move your eyes to it. With visual confirmation, do the necessary.
With these done, you are down to your last GUMPS check. Turn everything on and brief the passengers for safety.
This would also be a good time to run through your missed approach procedures, even if you are in VFR conditions on an IFR approach. That’s part of the safety procedures that you should be thinking about in every approach.
Each cockpit is laid out differently and you should form your flow in a way that you get everything on the GUMPS check without too much distraction. That is the genius of the GUMPS check. It guides you through a once-over of the critical systems without having to divert your visual attention from the instruments or traffic outside or divert auditory attention from what’s going on on the radio.
GUMPS checks are especially valuable during single pilot operations where the workload for the pilot increases exponentially.
The Downside of a GUMPS Check
As much as I hate to admit it, there is a major downside to the GUMPS check. There are numerous pilots who I have sat with on BFRs who think that running GUMPS alone is enough.
This could not be further from the truth. The GUMPS check is an aid and is not intended to replace or displace the approved checklist. There are still several things on the checklist that you have to look at and configure for landing.
After some time of repeating the GUMPS check, pilots then completely lose the ability and discipline to run checklists, and when they have to, like on a BFR, it messes with their ability to fly the plane and follow a checklist.
Extended Uses of GUMPS Check Use
I use the GUMPS check in other phase transitions as well. I use it as a framework, knowing that not all words of the acronym would be relevant.
For instance, I run a GUMPS check just before positioning for take-off. Even after the checklist is done, I take a quick look at the gas tank selection lever, followed by a quick look at the gear lever (for flow sake), and get my hands to push the props and mixture forward. I make sure my pumps and switches are down as well.
When I get to cruise, I run the checklist as well. This became especially relevant after I had a BFR candidate who left his gear down throughout his flight. He only recognized it when it came time to run the landing checklist.