Landing ‘Aim Point Marking’ versus ‘Touchdown Zone Marking’

8 Answers

1. 
   

   
   

   John D. Collins on Aug 24, 2011

   Matthew,
    
   The AIM is correct.  The AIM point markers, the 2 big white bars, are intended to be used as the visual AIM point by the pilot. They roughly correspond to where the glidepath intercepts the runway surface. A 3 degree glidepath with a threshold crossing height of 50 feet will intersect the runway surface 954 feet from the threshold. Assuming the VASI or PAPI is aligned with the GS, it will provide visual guidance to roughly the same point.
    
   The touchdown zone markers are primarily intended to give the pilot distance markers for every 500 feet of runway and are not intended to be used as an aim point. On a long runway, they mark the first third of the runway, where touchdown is expected.  They are painted in pairs of three, two, and one stripe markings with a single three pair marking and two each of the other markings.  A long enough runway will have 5 Touchdown Zone markings for each runway and one Aiming point, so if both ends of the pavement are painted for precision markings, there will be a total of 10 markings. This takes up 3000 feet for a full set on each runway side. So a 10,000 foot runway will have markings on the first 3000 feet of the runway and the last 3000 feet of runway in the opposite direction. Shorter runways can’t use the full set, so the ones towards the middle of the runway get eliminated as necessary.
    
   In my Bonanza, after I flare over the Aim Point Marker, I will not touch down for at least another 500 feet, about where the second set of touchdown zone markers from the threshold are painted on the runway.  Since the touchdown zone markers are painted every 500 feet from the threshold, that means I would touchdown at the 1500 foot point. 

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2. 
   

   
   

   Andy Neumann on Aug 24, 2011

   Matthew,
    
   I can see why this is confusing.  You have the AIM saying the broad white bars 1000′ down the runway are the “aiming point”, but then you have the Airplane Flying Handbook (AFH) saying:
    
   “The point toward which the airplane is progressing is termed the ‘aiming point.’ [Figure 8-9] It is the point on the ground at which, if the airplane maintains aconstant glidepath, and was not flared for landing, it would strike the ground.”
    
   Two meanings… same words.  It’s probably best to say “aiming point marking” when talking about the paint stripes to reduce confusion between you and your students.
    
   Then what about the “touchdown zone”?  Is see this as more of a reference for high performance airplanes that eat up a lot of runway if they come in too fast or extend their flare trying to grease it on.  Part 91.175 also stipulates that commercial air carriers have to be in a position to touchdown within the touchdown zone to continue a landing from an instrument approach… so the touchdown zone does carry some legal weight.  I don’t believe there is any reason to teach your students that they MUST land in the touchdown zone.  I know I didn’t require that, although the pilot should always be able to land the airplane where he/she wants on the runway, whether that be the numbers or as John said, 1500′ down the runway. 
    
   For primary instruction, I always preferred the numbers as the aiming point.  Some instructors my prefer otherwise. 
    
   By the way, on short field approaches and landings, I found that the aiming point pretty much correlates with the touchdown point if your airspeed is right and you reduce power to idle at the proper moment.  But yes, for a normal approach and landing, one would always float a little past the aiming point used on the approach.  

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3. 
   

   
   

   Matthew Beyer on Aug 24, 2011

   Thanks, this makes sense. From a runway marking perspective I can read the AIM as saying “these markings that look like this with the smaller bars” make up touchdown zone marker(s) with a nice helper of having some distance built in. And then the big unmistakable markings are the important aim point. It was just funny that even on all of my checkrides as well as training, we treated the big bars as touchdown point. Now makes sense, they are unmistakable and easy to say “touchdown there +- whatever”, cant confuse them. I too like using runway numbers as an aim point since they exist on precision and non-precision runways. Use it today as I was able to give the same instruction between the 2 different airports “the numbers are your aim point…”. It sounded consistent. Thanks guys

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4. 
   

   
   

   Brian on Aug 24, 2011

   “For primary instruction, I always preferred the numbers as the aiming point.  Some instructors my prefer otherwise. ”
    
   Agreed, but maybe for an uncommon reason. Ever look at something straight on and then from an angle? Notice how it appears to elongate when viewed from ever increasing angles? Numbers provide an easily distinguishable angular elongation if you will. Using this information I’ve found that, by getting the student to focus on an imaginary box around the numbers, they can often learn, quite quickly, how to judge their glide angle.
    
   As for all these definitions, keep in mind that, when talking about runways with these markings, they are typically designed with instrument procedures in mind. Simply making that known to the intuitive student who recognizes these discrepencies may help to put their mind at ease.

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5. 
   

   
   

   Earl Kessler on Aug 25, 2011

   I teach that if you follow the VASI, you will end up landing well beyond the beginning of the white bars.  The reason is that the round-out and flair take you floating well beyond where you are aiming.  So if you aim for the center of the numbers and ignore the red VASI lights, you will likely land at the beginning of the white bars.  The primary pilots who fly the VASI are in trouble if they go to an airport without one, so it’s a good idea to teach them to get a site picture that relies on their raw data eyeball judgement method without the VASI crutch.

   +10 Votes 11 Votes  1 Votes

6. 
   

   
   

   Scott Stahl on Aug 28, 2011

   This difference in distinction has to do with the type of airplanes that were used when defining the markings.
   The touchdown zone begins prior to the “aiming point” markings primarily because in a large turbine powered aircraft, the main gear can be 100′ or more BEHIND the cockpit.  Thus, if the pilot is aiming at the “aiming point,” the aircraft main gear may touchdown well before that point.  This is also related to the fact that there isn’t a lot of flare and travel in a large turbine airplane, where they tend to flare just enough to keep the nose off, and literally fly the airplane onto the ground.
   It can be confusing when considering the markings in a small airplane, because the size is so relatively small.

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7. 
   

   
   

   David Eberhardt on Nov 23, 2011

   referencing John Collins answer at the beginning here – having an aimpoint coinciding with the ILS glidepath (950 feet beyond the threshold) is great for heavy metal pilots (jets) but little old Cessna 172s and Cherokees and the like can find an aimpoint a little closer – I use the big runway number(s).
   This comes in handy when landing at the shorter airfields that small airplanes are known to visit.

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8. 
   

   
   

   David Eberhardt on Nov 23, 2011

   thumbs up to Kessler

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