4.0 DATA REDUCTION 
All film was sorted and catalogued for each event. Every event 
was recorded with the aircraft number, date, film roll, runway, and 
landing time. This was required since all data was to be compared 
with the aircraft MSDRS computer data. 
Film frames were sorted, starting from WOW every .5 of a second 
to 3.0 seconds before WOW. The film frame from each camera for 
each epoch of the event was measured on a PASS 2000 system, in 
addition to scanned images that were measured with our 
Digtab_Plus IP soft copy system. Control values were measured 
along with 5 points on the aircraft as illustrated in Figures 3 and 4. 
During this study WOW is defined as the point at which the smoke 
from the undercarriage tires is visible on the film frame. The point is 
thus defined for each camera to within one twentieth of a second. 
This point is not necessarily the point at which the WOW flag in the 
aircraft recording system is displayed. 
Three dimensional coordinate data were computed for the 
reference points shown in Figure 3 and 4. The data was 
transformed and compared to values obtained from the ground 
based photogrammetry. 
Utilizing the three dimensional coordinate data obtained points on 
the aircraft mid point 806 was computed for each epoch and 
event.(Figure 4.) The point 806 is very close to the CG of the 
aircraft (35 inches aft) and directly in line with the main 
undercarriage. Since the point 806 is so close tà the aircraft's CG it 
was used for the determination of airspeed and sink speeds found 
in Table 1. 
Airspeed was calculated using the distance travelled over the time 
taken between the epochs. The sink speed is calculated using the 
elevation differences taken between the epochs at point 806. The 
airspeed is displayed in Table 1. in Knots per second and sink 
speed has been reduced to feet per second. 
4.1 Accuracies of the final landing parameters 
After reviewing the data epochs within some events show forward 
and sink speeds, not having a smooth trend. This was caused by 
synchronization problems within the cameras and to poor image 
quality. In addition problems were encountered with film flattening, 
or consistency of film flattening during the exposures. The 
percentage difference between the airspeed and sink speeds are 
consistent and the problem occurs over the entire frame. 
As described, the frames were additional matched utilizing the 
timing target in each frame. The film rebate on some cameras was 
wider so there was a difference between the overall frame count. 
If the camera synchronization is out by a half frame or 1/40 sec. 
then the aircraft would have travelled forward by .87 meters. This is 
equivalent to 3.4 knots in the speed calculation.( ** Table 1.) 
The reference points coordinate accuracy is 25 mm in the object 
space. Frames were read every .5 seconds, a typical aircraft 
vertical movement in .5 seconds is 1.3 meters this provides a 
percentage of accuracy of 2 percent. This equates to an accuracy 
of .2 ft/sec in sink speed. 
  
  
  
  
  
  
  
Figure 5. 
5.0 CONCLUSION 
The purpose of this study was to provide a reasonably detailed 
analysis of the adaptability of photogrammetric mensuration 
procedures for determination of landing parameters of F18 aircraft. 
The photogrammetric data extraction process proved to be 
advantageous and cost effective. 
The landing parameters determined by photogrammetry was 
compared to the MSDRS data, the epochs compared within 10 
percent. This comparison it quit good, one has to consider that the 
WOW flag from the MSDRS data is not necessarily the same that 
is used for the photogrammetry. In addition even the frames that 
showed slight synchronization problem's data plotted to a XY plot 
show the same trend. 
Approximately 70 100 foot rolls of film were taken at the site. The 
cameras were mounted along the side of the active runway within a 
fairly difficult working environment (Figure 5). There were hundreds 
of takeoff and landings with various (armed) military aircraft. 
Communication and team liaison were very important, especially 
for coordinating photography and safety reasons, every item had to 
be secured and removed from the site at the end of the day's 
photography. 
| would like to thank the personnel at Canadian Air Force Test & 
evaluation lab for there support during this project. 
6.0 REFERENCE 
Albakyan K. "Use of Photogrammetry in Aviation equipment flight 
testing" : 
ISPRS Commission V symposium Zurich, Switzerland Sept. 1990. 
Garstang J. "CASB Engineering Branch Applications of Image 
Processing and Photogrammetry in Aircraft Accident investigation" 
Presentation at High Resolution Photodigitizing conference 
Phoenix, Arizona May 1989. 
Robertson G. "Aircraft Crash Analysis Utilizing a Photogrammetric 
Approach" presented paper ISPRS Commission V symposium 
Zurich, Switzerland Sept. 1990.