Jump to content
Sign in to follow this  
Ed Cesnalis

Headings within 5 degrees of N/S and VFR Cruise Altitude

Recommended Posts

For me its common to be flying  a heading like 178* and the reciprocal on the way home.

I feel all set up for a head-on with the guy flying 002* and we are both at 9,500 for appropriate VFR cruise altitudes that are designed to prevent such mid airs.  When you get around to north / south headings do they encourage collisions instead of providing the inherent protection?

Share this post


Link to post
Share on other sites

I feel nervous around these headings as well.  Sometimes at those headings I will fly a lower altitude within 3000ft AGL so that I can select any altitude I want, and select something oddball like 3300 MSL. 

Share this post


Link to post
Share on other sites
24 minutes ago, FlyingMonkey said:

I feel nervous around these headings as well.  Sometimes at those headings I will fly a lower altitude within 3000ft AGL so that I can select any altitude I want, and select something oddball like 3300 MSL. 

me too but when I'm crossing but deep valleys its not worth descending 7,000'.

Share this post


Link to post
Share on other sites

I had a near miss several years ago due to this same thing. It was a hot Summer day with your typical Midwest poor hazy visibility, between 3 and 5 miles. I passed a Pitts Special by not more than 200 feet at the same altitude. I had no time to react, and have no clue if the other guy saw me.

I suppose that you can fly off altitude a little bit, but then it puts you closer to IFR traffic if there is any.

Share this post


Link to post
Share on other sites
49 minutes ago, Ed Cesnalis said:

I think we are making a case for using ATC radar services for collision avoidance when cruising N/S and without ADSB. 

 

 

Yes, but even ADS-B and flight following won't save you from an airplane with no installed transponder (though granted that is rare these days).

Share this post


Link to post
Share on other sites
23 minutes ago, FlyingMonkey said:

Yes, but even ADS-B and flight following won't save you from an airplane with no installed transponder (though granted that is rare these days).

I have been flying one quite a lot over the past few months.

Share this post


Link to post
Share on other sites

With regard to altitude reporting and transponders. In my opinion, all operators who operate in congested airspace, whether VFR only or VFR/IFR, are well to spend the extra money and have both 91.411 an 91.413 inspections done on your aircraft. The VFR (91.413) only check does not verify altitude reporting accuracy. If your system uses gray code to communicate between the transponder and the encoder, it is very easy to lose a code line which can amount to hundreds of feet in reported altitude error. Also keep in mind that if any maintenance is done on the aircraft where error can be introduced into the system (transponder R&R, encoder R&R to name a few), the system techniquely must be checked, regardless of whether operating VRF only.

If you guys have GTX330 transponders installed, keep in mind that there is an AD against them for certain software level issues. There is also an AD for KT-76A King units. I have inspected numerous aircraft in the past where these AD's had been missed for years. There are several AD's for United altimeters too, but as far as I know, CT does not use United units.

It is unlikely that the AD's would apply in your guys case, unless a non-compliant replacement unit was installed at some point.

Share this post


Link to post
Share on other sites

With regard to ADS B. Vertical separation is still going to be based on pressure altitude. That takes you back to the altitude reporting system in every aircraft (except those without electrical systems like I think Tom was referencing). That is why that system needs to work properly.

Share this post


Link to post
Share on other sites

If one decided to "spend the extra money" and get both checks done on the transponder, what is the legal downside?  If the transponder fails the altitude accuracy check, is the transponder/encoder going to be marked as unairworthy and ground the airplane until "fixed"?  If so, that is a real downside, and a true risk in an airplane that has probably never gone through that check in its entire life, even at the factory.

Share this post


Link to post
Share on other sites

Flying Monkey,

If you had the full "IFR"  inspection done, and the system failed some portion of the inspection, then you are correct that It should not be approved for return to service until fixed. This inspection is done (or should be done) on every aircraft before it leaves the factory. Although, if you don't fly in airspace that requires its use, then you could probably do go.

Earlier, guys were talking about the benefits of flight following. A properly working altitude reporting system would be necessary to fully benefit from this.

The danger is that your aircraft may be reporting to ATC, a different altitude than you are actually flying on. Spacing decisions could be effected.

I am not saying that I think that a VFR only guy should go to the additional expense every 24 months, but I think that in the context of a discussion about near misses, it is worth mentioning this maintenance.

Also, removing and replacing many panel mounted radios does fall under the heading of "preventive maintenance" as defined in part 43 app A item 31, however transponders are excluded from this because R&R of a transponder would necessitate a recertification of the integrated system (even if it was an A&P or Repairmen who R&R'd the unit). I mention this because owners should know that if their transponder has been removed and replaced, there is a possibility of altitude reporting errors. In my experience it is fairly uncommon, but I have seen it a few times.

The GTX330 can display reported altitude on the screen, but I have seen differences between what the display shows, and what is coming out of the antenna when there is a problem with these transponders.

How I interpret the relevant regs is that they would rather an aircraft not report altitude at all, then report erroneous altitude.

Share this post


Link to post
Share on other sites

Could you not accomplish the same goal for VFR flight without the certification hassle by occasionally:  verifying altimeter settings, then asking ATC to report your altitude, and comparing to what you are seeing in your instruments?

Share this post


Link to post
Share on other sites

The only thing to keep in mind is that that technique only checks that one altitude. Reporting equipment switches over at 100 ft increments. The way the code works, you could be reporting correctly at 3300, but erroneously reporting by several hundred feet at say 3400 or 3200.

I do agree that cross checking with ATC is better than nothing though.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×