There are several ways to address this problem, this is one person’s approach. Irrespective of the approach taken, all aircraft required to comply with FAR 25 (and it’s equivalents) MUST make full analysis of all obstacles in the Takeoff path until reaching 1500 feet, or a higher altitude if dictated by obstacles.
Ideally (mandatory in some states) this higher safe altitude should be the MSA. (In Australia this is mandated in the AIP, but surprisingly, not in the applicable performance regulations, CAO 20.7.1B).
If we are to contain an EOSID procedure within the MSA altitude constraints, that implies that we must reach Safe Altitude within 25 miles, yet, for a 2 engined aircraft 1st, 2nd, and 3rd segments will often exceed 30 miles. Thus, it may be easily seen that for a 2 engined aircraft at it’s limiting weight, a turn is not desirable, but a necessity if we are to stay within 25 nm.
A certain Obstacle Analysis provider beginning with J (who have a far bigger litigation budget than mine) don’t provide any EOSID if there are no limiting obstacles within 30 miles straight ahead. Fine, but what do you do at 30 miles (often still in the 3rd segment)? I cite Melbourne RWY 34 as an example.” J” sees no problem straight ahead within 30 miles, so, after providing an increased Minimum Acceleration Altitude, lets you go and fly without any special procedure. There might be a mountain at 30.1 miles (there isn’t in this case), but their system does not consider it. What is the MSA? There is none, at 30 miles you have no reference MSA. If you make a Left turn back at MAA (as you would if still in the 3rd segment), terrain contact is a distinct PROBABILITY. If you make a Right turn back, you will survive, but might be deafened by the constant “Terrain, Terrain” calls from the GPWS. Lots of near misses.
The modus operandi that I use in creating EOSIDS is to –
(1) Maintain Runway Track for as long as possible, within terrain constraints, but with a turn (after considering turn radius and lateral splay) inside 25 miles,
(2) After the turn, track to a Holding Pattern shaped “Safe Climb” area, where continued climb to MSA may be conducted. After reaching MSA, FAR 25 et al is discarded, and Pans-OPS (TERPS) take over. Sometimes this is a published Holding Pattern, but more commonly a developed Radio-Nav pattern with the lowest terrain.
(3) This then is the Takeoff Area that I develop, Initial Runway Track (sometimes a Runway end turn), Track or Tracks to a “Safe Climb” Holding Pattern, and the Holding Pattern itself. Throughout this entire Takeoff Area, flight may be conducted at MAA with obstacle clearance assured, even though still below the MSA.
The basic Tracking requirements are as FE Hoppy describes them, i.e. the required Track (NOT HEADING) with a 7 Degree and 8 Minute splay on either side, plus 90M. The Splay continues until intersection with approved Radio Nav Tracking, whereafter the Radio-Nav tolerances apply.
Alternatively, for aircraft with on-board ability to fly Track, the lateral splay may cease upon reaching a nominal parallel margin. (I think that the Australian margin is too small, and use 1852M (1 nm), and 2 nm in the Holding Climb).
Before you can do any of this, you will need a GOOD obstacle analysis, and, guess what? Pilots are not issued with good obstacle data, unless you’ve had it supplied by the Company or a contract supplier. Australia is the exception with good Public Domain Obstacle GRADIENT data from Supplementary Takeoff Distances, but this is limited to 15,000 M (8 miles), a damned good start, but at a 1.6% Gradient, that will only “protect” you for the first 800 feet. After that, you’re on your own to MSA, or Minimum Radar Vectoring Altitude.
The “Normal” data given pilots, e.g. Approach charts are a long way from good enough. They only show the major obstacles, not the smaller “closer in obstacles” that are gonna getcha. Consider a 100 ft radio mast 1 mile from the runway end, being so low it will not be shown on any of the “regular” charts, but, for a 2 engined aircraft it IS a CRITICAL Obstacle after considering 1st Segment. A 500 ft obstacle at 6 miles from the Runway end will probably be shown on the chart, as it is higher. It LOOKS threatening, but, in fact, is not a critical obstacle.
So what to do? First, obtain data for the more dangerous closer in dangerous stuff. Easy in Australia, obtain Type ‘A’ charts elsewhere. (OLS charts are great if you can obtain them. J_T can, but he has friends in high places). After the limit of this closer in (note that I didn’t say close in) data, obtain High detail topographical charts with close contour intervals. For the proposed EOSID, account for the CVA (Chart Vertical Accuracy) at the next highest contour, CHA (Chart Horizontal Accuracy) all the way, build up a series of obstacle “steps”, and finally, obtain the elevation of the highest obstacle in the entire Takeoff Area. To all obstacles, make allowance for trees, man-made structures etc.
Plot the EOSID on the Topo chart, and apply the splay. Consider the maximum and minimum turning radii for all turns in the procedure.
Run a series of Runway Used Vs distance to obstacle performance checks to “zero-in” on the optimum Field/Obstacle limit considering 1st and 2nd segment climbs. Note the LOWEST Gradient usable for the 2nd Segment Climb (Important).
Calculate the height of the Highest Obstacle in the entire Takeoff Area above the Lowest point on the Runway. Multiply this Delta H by the Lowest 2nd Segment Gradient plus 0.8%, and divide by the Lowest 2nd Segment Gradient. Add to this the Highest Runway Elevation + 35 feet (or 50 feet for a Runway End Turn). This is the Minimum Acceleration Altitude (MAA). (I further increase MAA for the lowest AFM Temperature allowed, a cold weather correction, some don’t do this).
That’s the “back of a Postage Stamp” version, there’s a lot more to it, but Danny has band width limitations.
Now, what do you want to do? Aim it and go, hoping for the best, or insist that your operator spend a few (quite a few) bucks on getting proper airport analysis and EOSID development?
VERY IMPORTANT NOTE – The “J” that I spoke of in derogative terms earlier is DEFINATELY NOT John_Tullamarine, he’s a true professional. (Use your imagination).
Fly safe – Avoid the rocks!
Regards,
Old Smokey