bush pelican
19th Nov 2003, 12:21
'I do not mind lying, but I hate inaccuracy'
-Samuel Butler.
'THE BEST DEFENCE AGAINST A CLOSE ENCOUNTER IS AN EFFICIENT SCAN PATTERN''
NAS Ref. guide pg 24 & 47.
There have been some excellent research articles published on See & Avoid.
In 1991 BASI published an air safety report, ' LIMITATIONS OF THE SEE AND AVOID PRINCIPAL'
The report concluded,
' BASI considers that See and Avoid is completely unsuitable as a primary traffic separation method for scheduled services'
The RISK is no less, and in fact could be greater for the GA pax transport fleet due to their increased exposure to unknown traffic, higher workload, smaller aircraft and other factors.
Another study is that by Neale Fulton in the CSIRO-DIT Technical Report, ' AN OBJECTIVE ANALYSIS OF THE SEE AND BE SEEN HAZARDS IN MODERN AIR TRAFFIC CONTROL SYSTEMS' March 1994.
He states, ' Visual scans can be made more efficient by alerting the pilot through communication, as to where to look for conflicting traffic. For unalerted and alerted scans, modelling establishes that to achieve the acceptable failure rate, 52 and 28 seconds respectively, are required to acquire, perceive and respond to the threat.' 'Analysis shows that the performance of visual acquisition is highly dependant on both the cruising level rule design, and the availability of appropriate communications, ( air to air, air to ground, TCAS ) to alert pilots of potential threats and to assure effective use of human sight'
At 52 seconds a C340 is 5.2 kms away (aprox) and is 5mm wide in your screen.
Another excellent and practical discussion on this topic from a regional airline pilots perspective was written by Captain Keith MacKenzie, a Dash 8 training captain, and published in Asia Pacific Air Safety, June 1998 pg 10-13. entitled ' A Regional Airline Pilot's Perspective of SEE AND AVOID." Get it if you can.
Keith's words from the past are uncanny in their application to the situation today.
'SUMMARY.
A pilot's normal response to a traffic alert report is to prioritise the workload, increase the outside scan rate, and modify the descent or climb profile to avoid the conflict until the conflicting traffic can be identified and passed, or when not seen, separated by distance and altitude.
'See and Avoid' is an unsafe and dangerous principal for separation of RPT aircraft from VFR aircraft. The passengers are under the misconception that all aircraft around them are known to the pilots, and that their safety is assured. ( what a legal time bomb. BP ) .........
Radio is also an essential element in separation; however the information provided to the VFR fraternity in the use of Class E airspace is to essentially remain silent and not use the radio unless suffering an emergency or seeking radar advice. Traffic separation by radio is left to the whim of the least experienced ( and possibly the least current ) pilot. Mandatory carriage and use of radio is essential....'
All these papers should be easily procurable from aviation libraries or on the web. They are so conclusive that no one looking at them will be in any doubt as to the pup NAS is trying to sell us.
' IT IS ALWAYS THE BEST POLICY TO SPEAK THE TRUTH, UNLESS OF COURSE YOU ARE AN EXCEPTIONALLY GOOD LIAR'
-Jerome K Jerome.
Re Skin-Frictions comments.
It is obvious to anyone that operates any light twin that there are many times when a scan is interrupted.
Mike's flight was a rehearsed best case scenario and it showed. Field research has shown that the average distraction time from scanning to attend to cockpit matters is 30 to 50 seconds. If your traffic arrives at this time then BINGO!
I would be interested to know from pilots whether a scanning regime such as recommended in the guide (pg 24 & 47) is a common practise. i.e 18 secs to scan outside and then about 6 inside. Last time I checked it was about every 3-4 mins per outside scan for me. Also, it would be interesting to see some research on the fatigue outcomes for that regime over say a 2 to 4 hour flight. Me thinks pretty terrible.
Finally , if the statistical chances of a collision under NAS are so low as to not be of relevance or concern, why don't we be politically un-correct and say so?
-Samuel Butler.
'THE BEST DEFENCE AGAINST A CLOSE ENCOUNTER IS AN EFFICIENT SCAN PATTERN''
NAS Ref. guide pg 24 & 47.
There have been some excellent research articles published on See & Avoid.
In 1991 BASI published an air safety report, ' LIMITATIONS OF THE SEE AND AVOID PRINCIPAL'
The report concluded,
' BASI considers that See and Avoid is completely unsuitable as a primary traffic separation method for scheduled services'
The RISK is no less, and in fact could be greater for the GA pax transport fleet due to their increased exposure to unknown traffic, higher workload, smaller aircraft and other factors.
Another study is that by Neale Fulton in the CSIRO-DIT Technical Report, ' AN OBJECTIVE ANALYSIS OF THE SEE AND BE SEEN HAZARDS IN MODERN AIR TRAFFIC CONTROL SYSTEMS' March 1994.
He states, ' Visual scans can be made more efficient by alerting the pilot through communication, as to where to look for conflicting traffic. For unalerted and alerted scans, modelling establishes that to achieve the acceptable failure rate, 52 and 28 seconds respectively, are required to acquire, perceive and respond to the threat.' 'Analysis shows that the performance of visual acquisition is highly dependant on both the cruising level rule design, and the availability of appropriate communications, ( air to air, air to ground, TCAS ) to alert pilots of potential threats and to assure effective use of human sight'
At 52 seconds a C340 is 5.2 kms away (aprox) and is 5mm wide in your screen.
Another excellent and practical discussion on this topic from a regional airline pilots perspective was written by Captain Keith MacKenzie, a Dash 8 training captain, and published in Asia Pacific Air Safety, June 1998 pg 10-13. entitled ' A Regional Airline Pilot's Perspective of SEE AND AVOID." Get it if you can.
Keith's words from the past are uncanny in their application to the situation today.
'SUMMARY.
A pilot's normal response to a traffic alert report is to prioritise the workload, increase the outside scan rate, and modify the descent or climb profile to avoid the conflict until the conflicting traffic can be identified and passed, or when not seen, separated by distance and altitude.
'See and Avoid' is an unsafe and dangerous principal for separation of RPT aircraft from VFR aircraft. The passengers are under the misconception that all aircraft around them are known to the pilots, and that their safety is assured. ( what a legal time bomb. BP ) .........
Radio is also an essential element in separation; however the information provided to the VFR fraternity in the use of Class E airspace is to essentially remain silent and not use the radio unless suffering an emergency or seeking radar advice. Traffic separation by radio is left to the whim of the least experienced ( and possibly the least current ) pilot. Mandatory carriage and use of radio is essential....'
All these papers should be easily procurable from aviation libraries or on the web. They are so conclusive that no one looking at them will be in any doubt as to the pup NAS is trying to sell us.
' IT IS ALWAYS THE BEST POLICY TO SPEAK THE TRUTH, UNLESS OF COURSE YOU ARE AN EXCEPTIONALLY GOOD LIAR'
-Jerome K Jerome.
Re Skin-Frictions comments.
It is obvious to anyone that operates any light twin that there are many times when a scan is interrupted.
Mike's flight was a rehearsed best case scenario and it showed. Field research has shown that the average distraction time from scanning to attend to cockpit matters is 30 to 50 seconds. If your traffic arrives at this time then BINGO!
I would be interested to know from pilots whether a scanning regime such as recommended in the guide (pg 24 & 47) is a common practise. i.e 18 secs to scan outside and then about 6 inside. Last time I checked it was about every 3-4 mins per outside scan for me. Also, it would be interesting to see some research on the fatigue outcomes for that regime over say a 2 to 4 hour flight. Me thinks pretty terrible.
Finally , if the statistical chances of a collision under NAS are so low as to not be of relevance or concern, why don't we be politically un-correct and say so?