MH370 Flight Path Model version 16

Richard Godfrey
9th December 2015

 

I have updated my MH370 Flight Path Model to include a simulation of the Cost Index (CI) at ECON 52, now that the CI has been made available in the latest ATSB report. This updated model is labelled as version 16.0, the preceding version 15.1 having been described here.

The model version 16.0 (Excel spreadsheet, 2.5 MB) may be downloaded by clicking here.

I retained a late final major turn (FMT) starting at 18:37:24 and 15.6 NM before the waypoint IGOGU.

I also retained a step climb to 39,000 feet.

The resultant end point is located at 38.4S 87.7E.

Update 10th December:

Version 16.1 of the Flight Path Model is now available here. Version 16.0 entailed a constant speed being used between ping arcs 6 and 7, whereas a deceleration would be expected (a value of -0.315 knots per second has now been used here in v16.1, in line with Brian Anderson’s analysis).

The resultant end point is now 38.2S 88.0E.

Thanks to Brock McEwen for pointing this out.

Introduction
Many people are frustrated by the lack of a positive outcome in the search for MH370, and a determination of what happened onboard to cause its loss.

A Single Location From Three or More Data Sources
One would think with all this data, we should be able to determine exactly what happened to MH370. However, there is only one data location that is confirmed by three or more data sources and that is the take-off point (which does not help us much to determine what happened to MH370):
a. The ATC Transcript gives the cleared for take-off communication at 16:40:38.
b. The ACARS Position Report at 16:41:43 shows the aircraft at an altitude of 103 feet but 505 metres right of the centre line of Runway 32R.
c. Primary Radar at 16:41:54 (11 seconds later) picks up the aircraft half way down the runway at an altitude of 2 feet above the centre line of Runway 32R.
d. The Inmarsat satellite BTO and BFO data at the time of ACARS Position Report approximately confirms the location given by the Primary Radar.
e. The Aircraft Performance Data also confirms the location (take-off distance) and ground speed (take-off speed) given by the Primary Radar.

As one can see from the above, even this set of data does not completely agree.

[Note on b and c above:
– The runway at Kuala Lumpur is not level, but officially the field elevation is 69 feet above sea level (ASL).
– The Primary Radar indicated an altitude of 2 feet, which may be interpreted to mean 71 feet ASL.
– The ACARS take-off report of 103 feet ASL is a pressure altitude and the calibration may be normalised rather than set against the actual local pressure.
– The difference between those two altitude values is 103 minus 71 = 32 feet.
– That is just half the physical height of the aircraft, and the pressure sensor on the aircraft might be 32 feet off the ground.
– Thus there is no inexplicable discrepancy between b and c in terms of the aircraft altitude, but the transverse discrepancy (ACARS indicating the aircraft to be 0.5 km to the side of the runway when it was obviously on the runway) remains.]

Only Three Post-IGARI Locations Based On Two Data Sources
Following take-off there are 70 data points where two sources agree. However, 67 out of those 70 data points are prior to reaching the waypoint IGARI. Therefore we do not have a problem thinking that MH370 flew 38.6 minutes to waypoint IGARI (which also does not help us much to determine what happened to MH370); it is what happened thereafter which is the problem, due to lack of data.

Near IGARI the mystery begins (no VHF, no handover to Vietnam ATC, no transponder, no ACARS, no SATCOM, departure from Flight Plan).

Let me consider now the remaining three locations (for which two data sources agree) post-IGARI.

A. The first location is in the Straits of Malacca, 67.7 minutes after waypoint IGARI, flying in almost the opposite direction at a point where the aircraft weight is finally down to the maximum allowed landing weight (assuming no fuel was dumped): (a) The Primary Radar data shows the aircraft 10 NM beyond waypoint MEKAR following Flight Route N571 at 18:22:12. (b) The Inmarsat satellite BTO data 195 seconds later matches the aircraft location, direction and ground speed extrapolated from the Primary Radar data. (c) The Inmarsat satellite BTO and BFO data another 168 seconds later matches the aircraft location, direction and ground speed extrapolated from the Primary Radar data.

B. The second location is in the Southern Indian Ocean some 5.8 hours later; this location is defined by: (i) The arc described by the Inmarsat satellite BTO data at 00:19:29 and (ii) the arc described by the fuel range, the intersection of the two arcs giving a location. There are two problems with the Fuel Range data however:
(a) Where is the centre of the arc (or how far did MH370 fly along or near Flight Route N571 toward waypoint IGOGU before turning south)? (b) The precise fuel consumption rates of the MH370 Rolls Royce Trent engines. In addition the data matches a SATCOM log-on at the same time (assuming one accepts the idea that the SATCOM log-ln was the result of fuel exhaustion causing a power interruption). If you wish to match the Inmarsat satellite BFO data, you have to accept that the aircraft had a rate of descent of 5,394 fpm (53 knots) representing an angle of 6.3 degrees below the horizon. The BFO data can be made to fit the other data sources and is therefore not an independent data source.

C. The third location is in the Southern Indian Ocean just eight seconds later; it is defined by: (i) The point where the arc described by the Inmarsat satellite BTO data at 00:19:37 and (ii) the aircraft direction and ground speed extrapolated from the preceding location (B above). This is uncertain because the aircraft may have been turning. Flight simulations have shown that a turn develops after fuel exhaustion. The Inmarsat satellite BFO data can also be made to match, if you accept that the aircraft had a rate of descent of 15,873 fpm (157 knots), representing an angle of 18.8 degrees below the horizon. As mentioned before, the BFO data is not an independent data source.

Conclusion
In summary, we have a lot of data, but not much information based on two or more independent sources: thus there is very little data that helps us to determine precisely what happened to MH370.

We know that, if the aircraft speed profile was maintained between 18:28:12 and 19:41:03, the aircraft did not fly directly south from 18:22:12 to reach the arc described by the Inmarsat satellite data at 19:41:03.

How far the aircraft flew along or parallel to air route N571 toward waypoint IGOGU is the key to determining how far south the aircraft finally ended up.

We can have strong confidence that, for MH370 debris to wash up on Réunion when it did, the aircraft headed into the Indian Ocean.

We know there is a consistent set of single BFO data points indicating that the aircraft was headed southwards from 18:39:53 onwards.

We also know there is a consistent set of BTO and BFO data points from 19:41 onwards indicating that the aircraft proceeded in the same general direction and speed. Brian Anderson showed, in a post published last March (Deducing the Mid-Flight Speed of MH370), that the True Air Speed at the nearest point to the Inmarsat satellite (at about 19:52:15) was around 484 knots and consistent with the final reported ACARS value. Yap Fook Fah showed, in a post also published in March (Autopilot Flight Path BFO Error Analysis), that the BFO data from 19:41 onwards is consistent with an autopilot flight.

At the end of the day, our analysis has the same fundamental limitations as faced by the many others who have put forward their hypotheses. We are trying to connect the dots, except there are too few dots we are really sure about where it most matters. And that, essentially, is why the crash site of MH370 is yet to be identified.

Questions about the Radar Data for MH370

by Victor Iannello, ScD
September 24, 2015

A PDF version of this report may be downloaded by clicking here or here (540 kB).

Notice: The views expressed here belong solely to Victor Iannello and do not necessarily represent the views of the Independent Group (IG), or any other group or individual.

Introduction

In a recent paper [1], we analyzed the position and time data derived from the publicly-available radar data for MH370, and made the following observations:

• After the turn back towards the Malay Peninsula, the flight path recorded by civilian primary surveillance radar (PSR), civilian secondary surveillance radar (SSR), and military radar are consistent with a flight at a Mach number (M) equal to 0.84 at a cruising level of FL340.
• If the aircraft did fly at a steady M = 0.84, then the timestamps for some of the PSR contained in the Factual Information (FI) [2] are offset by about 35 seconds.
• After the left turn at around 17:23:38 UTC, the aircraft might have descended from FL350 to FL340 and accelerated from a ground speed of 473 kn to a ground speed of greater than 500 kn.
• In the FI [2], the PSR data between 17:47:02 and 17:52:35 UTC are attributed to the radar site at Kota Bharu, but more likely were collected by another radar site. The PSR data between 17:30:37 and 17:44:52 are correctly attributed to Kota Bharu.
• In the FI [2], it is stated that Indonesian military radar recorded MH370 as it traveled toward IGARI but not as it traveled back over Malaysia. One explanation is that Indonesian radar site was powered down after midnight, local time.
• The sharp turn to the left at around 17:23:38 UTC is unexplained, and could be due to either an inaccurate graphical portrayal of the radar track, or crossing radar tracks from two aircraft.
• The curve in the radar path close to Kota Bharu can be explained by “slant range” due to high altitudes and close distances.
• Fuel consumption models which assume that MH370 flew near Long Range Cruise (LRC) speeds and at cruising altitudes between 17:07 and 18:22 are likely accurate.

The estimated path and speeds for MH370 from takeoff to the last radar point [1] is shown in Figure 1.

Bob Hall [3] used the software package STK to calculate the radar range for various military radar installations in Thailand and Malaysia that may have seen MH370. The range calculations were solely based on the line-of-sight between the target aircraft and the radar head, including any obstruction caused by terrain features such as hills and mountains. The calculations were performed for a geometric altitude of 37,000 ft, which corresponds to a pressure altitude of about 35,000 ft (i.e. FL350) over Malaysia at the time of the disappearance. The results are shown in Figure 2. (The path shown for MH370 in Figure 2 is not exactly correct because at the time the plot was generated in October 2014, the details of MH370’s path as derived from the radar data were not known.)

Based on the work performed in [1] and [3], we have developed a list of questions related to the radar data that would help the public to better understand this incident. We believe that the answers to many or all of these questions are known to the Malaysian investigators, and we see no valid reason for not making this knowledge available to the public.

Figure 1. Estimated path and speeds for MH370 from takeoff to the last radar point [1]. 

Figure 2. Range of military radar sites for an aircraft at 37,000 ft [3]. 

(A higher-resolution, bitmap version of Figure 2,
without the annotation at left.)

Questions

1. Was the turn to the left after IGARI captured by Malaysian military radar? It was in range of the radar head at Bukit Puteri, Jirtih, but near the range limits of Western Hill, Penang Island.

2. Was the turn to the left after IGARI captured by Thai military radar? It was near the range limits of the radar heads at Ko Samui Island and Khok Muang.

3. The turn to the left after IGARI was depicted in two ways. At the meeting with the next-of-kin (NOK) on Mar 21, 2014, at the Lido Hotel in Beijing, it was depicted as a looping, 270-degree turn to the right, as shown in Figure 3. By contrast, in Figure 2 of the ATSB report [4] from June 26, 2014, the turn is depicted as a sharp turn to the left. What is the reason for this discrepancy of the depictions of the turn after IGARI? Which of these depictions is correct?

Figure 3. Flight path shown to the NOK on March 21, 2014, at the Lido Hotel in Beijing.

4. The depiction of the turn after IGARI as a sharp turn to the left seems to be beyond the performance limitations of a B777. Was the turn accurately depicted in Figure 2 of the ATSB report [4] from June 26, 2014?
5. Is it possible that the sharp turn to the left after IGARI is actually the crossing of the radar returns from two aircraft?
6. What specifically led investigators to conclude that the unidentified aircraft that crossed the Malay Peninsula and proceeded up the Malacca Strait was indeed MH370?
7. On March 21, 2014, military radar data from an unidentified aircraft (assumed to be MH370)) above the Malacca Strait was presented to the NOK at the Lido Hotel in Beijing, and shown in Figure 4 . Were these radar returns captured by the radar installation at Western Hill, Penang Island?

Figure 4. Radar data shown to the NOK on March 21, 2014, at the Lido Hotel in Beijing.

8. At the time of disappearance of the unidentified aircraft from military radar at 18:22 UTC, the aircraft was within range of the Thai military radar head at Phuket. Did this radar station also capture this unidentified aircraft? Is so, what was the path after 18:22?
9. In Figure 1.1F of the FI [2], the radar returns between 17:30:37 and 17:52:35 are attributed to the primary surveillance radar (PSR) returns as captured at Kota Bharu. The unidentified aircraft was supposedly captured by Kota Bharu radar until it reached just south of Penang, which exceeds the 60 nm range of the radar head at Kota Bharu. How is it possible that the radar returns are correctly attributed to Kota Bharu for the entire interval between 17:30:37 and 17:52:35? Is it possible that the radar returns after 17:44:52 were captured by another installation such as the terminal approach radar at Butterworth?
10. What was the cause of the disappearance of radar returns from the unidentified aircraft after 17:44:52, 17:48:39, 17:52:35, and 18:07:16? Some believe this indicates the unidentified aircraft was descending at these times, but this interpretation is not consistent with calculations [1] that indicate that the unidentified aircraft flew at nearly constant 498 KTAS, corresponding to M=0.84 at FL340.
11. Is it possible that the disappearance of the unidentified aircraft from radar was due to electronic countermeasures such as jamming and deception?
12. In Figure 1.1F of the FI [2], there is a point labeled as P1706 that is located near Kuala Lumpur International Airport (KLIA), but has a timestamp which appears to be 17:28:41, which should place the target much closer to the left turn after IGARI. What is the reason for this anomalous capture?
13. As described in [1], there seems to be a time shift of about 35 sec from some of the radar returns attributed to the PSR head at Kota Bharu. Are all of the timestamps from Figure 1.1F of the FI [2] referenced to a single clock, or at least from synchronized clocks?
14. In Figure 4, there is an anomalous return (as labelled in black by VI) at 02:07:06 MYT (18:07:06 UTC) that is north of the other returns and is not explained. Was this target possibly another aircraft?
15. The radar images presented to the public to date show no other traffic. What other traffic was in the vicinity of MH370 and the unidentified aircraft?

References

[1] Victor Iannello, “Some Observations on the Radar Data for MH370”, August 18, 2015. Also available here.

[2] Malaysian ICAO Annex 13 Safety Investigation Team for MH370, “Factual Information, Safety Investigation for MH370”, March 8, 2015; updated April 15, 2015.

[3] Bob Hall, private email to the Independent Group, October 16, 2014; used with permission.

[4] Australian Transport Safety Bureau (ATSB), “MH370 – Definition of Underwater Search Areas”, June 26, 2014.