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Home > Dr JB Lim's Corner > Aviation enthusiast Dr JB Lim's account of his trip to China...
Aviation enthusiast Dr JB Lim's account of his trip to China...
Flying - Dr JB Lim's Corner
Wednesday, 06 May 2009 11:50

I reproduce Dr JB Lim's account of his flight (cc to me) to his friend, Xavier Goh. He is very passionate about anything on flying and goes to the extreme to dissect his journey scientifically. This is only for those who love facts and figures (apologies - the figures do not come out legibly due to the reformating)... Captain Lim.

I first flew from KLIA (Malaysia) for Shenzhen, China at exactly 18 seconds past 2:32 a.m. in the morning (2:32:18 a.m.). This was the precise moment in time when the plane’s wheels lifted off the runway at KLIA. After hurtling in the skies all night at a height of over 8 km above the Earth surface at a near constant velocity of 465 knots (860 kph) at a bearing (path of flight) 54 0 NE, we finally touched down at Shenzhen Int’l Airport when the plane’s wheels touched the runway at precisely 4 seconds past 6:04 a.m. (6:04:04 a.m.).

The velocity of the plane changed slightly by just a few knots every few seconds probably due to the directions of the cross, head and tail winds outside. The thrust of the engines probably did not change much I guess.

On arrival we took a coach to Guangzhou for a city tour, breakfast-lunch and shopping. In the afternoon we took a one hour domestic flight from Guangzhou at precisely 15 seconds past 1:31 p.m. (1:31:15 sec p.m.). This again was the exact moment in time when the wheels lifted off the runway at Guanzhou Int’l Airport, and it landed at precisely at 03 seconds past 2:30 p.m. (2:30:03 p.m.) when the plane touched the runway at Changsha. Both flights were by Shenzhen Airlines.

The next day after arrival at Changsha, we toured the entire Zhangjiejia area where all the mountains and parks are.

The following day again, we went to another mountain area called Yuanjiejie and Tianzi Moutains, and took the fantastic mountain elevator (lift) up to the mountain top, toured the whole area in the rain, thick fog and chilly mountain winds registered at 10 0 Celsius in spring.

High Speed Elevator to the Mountains:

I salute those engineers who could built a high speed elevator leaning against the vertical slopes of a high mountain, and zoom us up to the top of the mountain in just 2 minutes. It was to me an engineering wonder of this world.
After touring the mountain, we then came down by cable car – much steeper and longer than our Genting cable cars. Of course we also went to the usual factories selling tea, silk, knives, etc.

From Hunan to Hubei:

The following day, we left Hunan Province for Jingzhou and traveled the entire day from Hunan to Hubei till we reach Yichang (Xiaoxita) past midnight in Hubei Province. Here we encountered problem entering the security check point because we did not have the permit to go further. It was still another about 30 km to the port at Huanglingmiao (still in Yichang). The coordinates of Huanglingmiao are: 30° 50' 41" North, 111° 5' 17" East

So we have to wait here in the middle of the night which gave me the golden opportunity to do some astronomy in the clear dark skies in the middle of Hubei Province in rural China. We lost a lot of time arriving as we also lost the way to the Yangtze River embarkation point despite the coach driver armed with a GPS device and the help of two other local Chinese tour guides and a Malaysian tour leader – all of them on board the coach. I too was armed with 2 Global Position Systems (GPS), but to me reading them in a strange place was as good as, not knowing my position.

Late Dinner:

We also missed our dinner at a pre-arranged restaurant, supposed to be somewhere in Yichang Province. Anyway we went to another private unscheduled restaurant (geographical coordinates according to my GPS was N 30 deg 42’ 35.6” / E 111 deg 18’ 25.8”) in Yichang city and had a sumptuous dinner there at 10:19 p.m. at the expense of the travel agent.

After dinner we traveled on but were still not sure if we were on the right direction until we finally have to reach an entry check point towards where the ship was waiting for us.

Stopped at Check Point:

We still have another over an hour journey to go after the check point before we could reach the ship. But we were stopped at the entry check point because we did not have a permit to go further. We were stopped here for over an hour in the middle of nowhere

Luxury Cruise Ship Waiting Finally:

Finally the local tour leader managed to solve this problem, and we then proceed to go to Huanglingmiao and managed to board the cruise ship only at 2:30 a.m. The geographical coordinates of Huanglingmiao where the cruise ship was docked waiting for us was: N 30 deg 50’ 34.1”/ E 111 deg 4’ 32.3”

The Horrendous Hydroelectric Dam:

Next day after breakfast we visited the hydroelectric dam by coach along the Yangtze, came back to the cruise ship for lunch. The geographical location of the hydroelectric dam according to my two GPS devices I carried along was North 30 0 50’ 5.4”/ East 111 0 1.0’ 5.0”. After lunch, we set sail into the 5-6 ship locks. This was quite an experience.

Ships Locks:

The geographical location of the first ship lock was N 30 0 50’ 6.8” / E 111 0 1.0’ 32.6”, and the last water lock location was N 30 0 51’ 35.1” / E 110 0 59’ 2.2”

The whole procedure going through all the ship water locks took some 4-5 hours to complete, before we managed to sail away into the open Yangtze for the rest of the 3-4 day and night cruise until we reached Chongqing city in the upper reaches of the Yangtze River.

The amount of water pumped in and out from each ship lock must be enormous. I do not know the length and breadth of each lock; else I could have calculated the rate and volume of water. I only know the rate of rise of water as about 1 metre every 10 seconds, but not the dimensions of each lock.

However each lock is huge as it can easily accommodate 6 big ships inside, with two abreast and 3 behind each other. Had I known the length and breadth of each ship, and the space between them I could have estimated the length and breadth of each lock, and knowing the rate of rise of the water from the depth markings on the walls, I could have easily calculated out the total volume, and also the rate of flow of water inside. I am passionately curious about this. But unfortunately I do not know the dimensions.

Chongqing City:

Chongqing City geographic location was: North 29 deg 34’ 6.0” / East 106 deg 35’ 15.9” near where the cruise ship was anchored. We visited a few places including the museum, the new village settlements where the villages were resettled when huge areas along the Mighty Yangtze was flooded due to the construction of the huge dam.

The itinerary of the Yangtze Cruise is attached in the file, but this was slightly changed for various reasons.

Flight and bearing data of plane and ship:

The average velocity of Shenzhen Airline plane from KLIA to Shenzhen Int’l Airport which I clocked using both my GPS devices was 465 knots (860 kph) at an altitude of 8,330 metres above sea-level. The path of flight (bearing) was 54 0 NE

The average speed of the cruise liner was 11.9 knots (nautical miles per hour) or 22 kilometers per hour,

The velocity of the plane of Shenzhen Airlines from Guangzhou to Changsha near landing was clocked at 377 knots (698 kph or 434 mph), and the bearing (direction of flight) was registered at 35 degrees NE.

This was recorded using my 2 compasses and two GPS instruments.

Conversion data:

1 knots = 1.85200 kph
1 mph = 1.609344 kph

I hope I have briefly answered your questions. I have an entire log book of data for velocity, altitude, bearing of ship and plane, geographical coordinates, date and time, air temperatures, humidity, air pressure, astronomical observation, etc over mid China etc if you are interested.


JB Lim


My apologies:

I am sorry for troubling you with the above and below info due to my chronic passion for measurements and scientific data. I thought I should share this out with you if you are just as passionate as me, else just delete them. They are just for my interest.

I was the only passenger who stayed up the whole night to take measurements and make observations of the night skies outside with the cabin lights darkened. My reading light was the only one on inside the entire cabin to allow me to take readings, while the rest of the passengers were all asleep. Not many share my hobby.

Dear Captain Lim,

I have collected some data for your info and comments. These to me were one of the most exciting moments during my trip. I know I am very amateurish as a ‘navigator’ or ‘pilot’ but that was the best I could do as a passenger with just a compass and a GPS.

I have to secretly switch on my GPS on during the cruise before the cabin crew asks me to switch them off. As spoken to you over the phone before my flight to seek your advice, I know I can never endanger the aircraft with a non-emitting device like GPS unlike a mobile phone.

Even with my mobile phone which also has a GPS, there was absolutely no transmission or emitting phone signals during the cruise at 10 km high.


JB Lim

Geographic Location North Latitude: East Longitude: Altitude

KLIA 2 0 45’ 16.7” 101 0 42’ 12.5” 85 meters
Shenzhen Airport 22 0 38’ 34” 113 0 48’ 46”

KLIA to Shenzhen = 2553.585 km (1586.7239 miles). Checked okay

Guangzhou Airport 23° 23? 33? 113° 17? 56?
Changsha Airport 28 0 11 11.6 113 0 08’ 39.1”

Guangzhou to Changsha = 530.208 km (329.4557 miles). Checked okay

Location Deg North Latitude: Deg East Longitude:

KLIA 2.75403 101.70416 (checked, okay)
Changsha 28.17874 113.11080 (checked, okay)

Chongqing Airport
(inside plane) 29 0 43’ 5.0” 106 0 38’ 14.3” 700 metres
Shenzhen Airport 22 0 38 8.2 113 0 48’ 59”

Chongqing to Shenzhen = 1061.9 km (659.8 miles)

Distance by Calculations and through Cockpit Announcement:

Shenzhen to KLIA = 2553.6 km = 1586.7 miles (by calculation) using spherical trigonometry or by applying the Haversine formula

Shenzhen to KLIA = 2730 km (according to the cockpit announcement)

Date Velocity Altitude Bearing Position of Aircraft
10 April 09 of Aircraft (m) (flight path) north lat / east long

Time (a.m.) (kph) (degrees min second)

3:44 a.m. 839 11,665 33 NE 8 d 28 m 56 s / 107 d 47 m 48.5 s
3:45 837 11,671 33 NE 8 d 35 m 5.1 s /107 d 52 m 4.1 s
? 833 11,682 34 NE 8 d 41 m 4.0 s / 107d 56 m 4.5 s
3:48 833 11,695 34 NE 8 d 47 m 14 s / 107 d 59 m 39 s
? 814 11,700 33 NE 8 d 51 m 44 s / 108 d 2 m 52 s
3:49 846 11,710 33 NE 8 d 58 m 26 s / 108 d 7m 19 s
3:50 820 11,714 33 NE 9 d 07 m 58 s / 108 d 13m 53 s
3:52 830 11,683 33 NE 9 d 14 m 22.9 s /108 d 17 m 18 s
? 839 11,870 33 NE 9 d 27 m 44 s / 108 d 26 m 45 s
3:55 858 11,700 33 NE 9 d 33 m 54 s/108 d 31m 9.0 s
4:05 850
4:15 a.m. 850
4:30 837 NE 13.38940 deg N / 111.09457 deg E
4:32 a.m. 817 NE
? 837
? 844
? 845
4:38 a.m. 852 NE
855 11,619 35 NE 14 d 28 m 19 s / 111 d 51 m 55 s
4:43 858 11,640 35 NE 14 d 34 m 30.9 s / 111 d 56 m 42 s
859 11,658 35 NE 14 d 40 m 29 s / 112 d 00 m 46.7 s
863 11, 672 35 14 d 44 m 46.9 / 112 d 06 m 15 s
855 11,685 33 14 d 48 m 44 s / 112 d 06 m 15 s
4:52 a.m. 243? 11,698 109? 15 d 34 m 9.8 s / 112 d 41m 39 s
4:56 a.m. 871
5:05 a.m. 877 11,625 34 NE 16 d 56 m 58 s /113 d 37 m 38.5 s
11,648 28 NE 17 d 03 m 39 s /113 d 40 m 15.3 s
837 11,653 03 NE 17 d 10 m 33 s / 113 d 40 m 38 s
5:10 827 0 N 17.68370 deg N / 113.71191 deg E
5:12 822
? 817

? 825 11,827 3 N 18 d 00 m 5.4 s /113 d 44 m 59 s
? 822 11,850 3 N 18 d 07 m 46 s / 113 d 43 m 34 s

5:34 a.m. No data was taken, but observation of the horizon was taken. There were signs of dawn breaking over the eastern horizon. The Earth curvature over the eastern horizon was perceptible with the faint glow of light just above the horizon. The color from the Earth below upwards to the skies were recorded in this order: A dark Earth below horizon ? deep orange atmosphere just above horizon ? higher up level of atmosphere above it was deep yellow ? light yellow ? light blue ? blue ? deep blue ? dark sky ? a bright planet possibly Venus high up in the still dark but very clear sky were observed They were recorded in my log book.

5:39 a.m. 770 kph 10,208 m 5 NE 21 d 14 m 16 s / 113 d 57 m 52 s
5:42 a.m. 798 kph 10, 263 6 NE 21 d 26 m 56 s / 113 d 59 m 20 s
5:43 a.m. 778 10,319 11NE 21 d 40 m 35 s / 114 d 01 m 59 s
5:45 776 10,369 m 12 NE 21 d 53 m 59 s / 114 d 05 m 14 s
? 777 10.406 13 NE 21 d 57 m 46 s / 114 d 06 m 6.6 s
5:59 a.m. 380 kph 713 m 256 deg Azimuth 22 d 48 m 13 s / 113 d 44 m 25 s

At this moment in time (> 5:59 a.m.), both my GPS system were switched off to prepare for further
descent and landing at Shenzhen International Airport. This was done as a precaution to prevent
disruption to the air-craft communication system.

The landing wheels touched the runway at exactly 4 seconds past 6:04 a.m. (6:04:04 am.) on 10 April
2009. The entire flight from KLIA (lift off) to touch down on the runway of Shenzhen Int’l Airport
took precisely:

3 hours 31 minutes 46 seconds or 3.5294444 hours (lift off to touch

The shortest possible ‘straight’ line distance between KLIA to
Shenzhen Int’l Airport over the curvature of the Earth by calculations
is 2,554 km. Hence the mean calculated velocity of the aircraft was
724 kph

But the announcement over the cabin that KL to Shenzhen distance
was 2730 km. Based on this announcement, the mean velocity was
773 kph.

Note: Please note the difference in the air distance between KLIA and
Shenzhen Int’l Airport based purely on calculations at sea level over
the curvature of the Earth without diverting even by a fraction of one
arc second, ‘straight as the crow flies’ Whereas a plane will have to
fly over10 km above the Earth’s surface adding a larger radius from
the centre of the Earth during the flight, and again descend again,
changing the geometry of flight.

Additional Mileage from path diversion:

Moreover, it has to divert flight path and bearing slightly during take off to
aim towards Shenzhen, and again during descend towards the direction of
the runway. All these add to the extra distances that cannot be calculated
out. I believe these ‘extra mileage’ can only be measured and recorded on
the plan’s computer. It is not practical attempting to calculate all these

Changing positions of aircraft:

Kindly note that the coordinates (location) of the aircraft changes so fast
since its velocity is some 10 times faster than the normal speed of a car that
it is almost impossible to write changing coordinates fast enough especially
the last column on the ‘arc second’ By the time I wrote them for that point in
time, the aircraft would have moved some 10 km or more away in less than
a minute.

The bearing of flight path given in the table, albeit mostly showed
quite a constant direction, yet they clearly showed changes in direction
during the last few moments before landing.

The GPS readings clearly showed evidence of a change in the flight path
(bearing) after 5:05 a.m. as it approached Shenzhen Airport. It was a
constant 35 deg NE since it left KLIA. All these add to extra distances from
the theoretical calculated values.

No measurement was taken during take off. The cruise velocity of the aircraft
by approximate mental counting of time lapse from the changing mileage
shown on my GPS was one kilometer every 4-5 seconds.

Flight data from Guangzhou to Changsha:

Data for this was not available because both my GPS could not catch the satellite signals inside the cabin.

However, approximately half-an-hour before landing at Changsha Airport, the cabin TV screen very briefly showed the map, flight path, and flashed the velocity of the plane at something like 433 mph or was it 698 kph? I am unsure, as this info was flashed on the TV screen for just a few seconds before they showed some stupid fighting movies on the screen instead.

Flight Data from Chongqing to Shenzhen:

Date Velocity Altitude Bearing Distance Position of Aircraft
18 April 2009 (kph) (metres) (flight path) Covered north lat / east long
Time (am/pm) (kilometers) (degrees min second)

11:22:46 a.m Lift off ? ? ? ?
11:27 a.m. 485 kph ? ? ? ?
11:28 a.m. 504 ? ? ? ?
11:30 609 4,948 Azimuth 190 S 29 d 38 m 42 s / 106 d 44 m 16 s
11:34 707 South 70.8 km
11:42 a.m. 931 ? ? ? ?
11:45 920 SE 232 km 28 d 1 m 7.3 s / 107 d 33 m 33.9 s
11:51 a.m. 948 SE 339 km
12:21 p.m. 915 10,634 Azimuth 135 S 24 d 15 m 21.6 / 111 d 11 m 41.2 s
12:27 p.m. 933 514 km 23 d 32 m 24.8 s /111 d 56 m 18.0 s
12:30 p.m. 887 8,621 Azimuth 133 580 km 23 d 15 m 12.4 s /112 d 15 m 12.4 s
12:36 683 8,400 Azimuth 132 643 km 22 d 43 m 32.4 s /112 d 49 m 45.0 s
12:40 585 4,198 SE 91 deg 681 km 22 d 36 m 15.4 s /113 d 07 m 48.1 s
12:45 p.m. 470 2,414 NE 65 deg 720 km 22 d 42 m 19.9 s /113 d 29 m 21.7 s
12:52 p.m. 244 412 Azimuth 151 750 km 22 d 41 m 11.9 s /113 d 47 m 20 s
12:53:40s p.m. touch down

Flight time Chonqing to Shenzhen: 1 hr 30 m 54 s
(lift-off to touch-down)

My best investment for flying:

I am extremely lucky to have a hand held GPS now to enable me to gather so much more information about the aircraft I was in than before. I used to have only a pocket compass which told me nothing other than just direction. Now I make full use of any scientific instrument available to me to satisfy curiosity about flying.

Captain Lim Column:

May I suggest you go to my friend, Captain Lim’s website? He is a senior pilot with a local airline. He writes a fantastic Q & A column about planes and flying which I always enjoy visiting and re-visiting. I always ask him a lot of questions about flying. His site can be accessed here:


He has suggested in one of his web entry Comparison of the Airbus A320's speed... that I buy a hand-held GPS. He wrote:

“Scientific mind and you have done a great job! Best regards, KH Lim.... I would like to suggest Dr. Lim to buy a handheld GPS receiver. ...”

Captain Lim did not know I have already done that even before he suggested that to me as I am mad about planes. Thanks Captain.


JB Lim

Location Deg Latitude: Deg Longitude:

KLIA 2.75403 101.70416
Changsha 28.17874 113.11080


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