EDTO BASICS & PROCEDURES
B737-800
EDTO MEANING AND CONCEPT
Extended Diversion Time Operations (EDTO) are operations beyond 60 minutes flying time to an enroute alternate aerodrome within the approved maximum diversion time. For the B737-800 in
Malaysia Airlines, the authorities have approved 120 minutes as Maximum diversion time. Before
we get confused by those statement, and go into detail, lets first have a look on what is a Non-EDTO
flight.
NON-EDTO FLIGHT
A non-EDTO flight is a flight where in all phases of that particular flight, the route is planned as
such if there is an emergency that requires a diversion, an adequate airport is always readily
available within 60 minutes or less through out the route. So lets say the flight is only 2 hours long.
Through out that 2 hours, you may be passing through and between multiple 60 minute radius
circles centered at an adequate aerodrome that are located in the vicinity of your route.
NON - EDTO FLIGHT
Based on the diagram above, you can clearly see that through out the whole flight, the routing is
always within the 60 minute radius circles. So at any time, if there is an emergency, there will
always be an airport within 60 minutes or less.
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!1
EDTO BASICS & PROCEDURES
B737-800
EDTO FLIGHT
An EDTO flight is exactly the same as a non-EDTO flight, except that through out the duration of
the flight, you will come across a segment where your nearest adequate airport that can be used as
an alternate is located more than 60 minutes. That segment is called an EDTO segment. So any
flight that has an EDTO segment, is an EDTO flight.
EDTO operations are allowed within a well-defined area of operations. The size of this area
depends on the maximum diversion time, the selected one-engine-out diversion speed schedule
and the number and location of the selected adequate diversion airports.
The EDTO Area of Operations is the area in which it is permitted to conduct a flight under EDTO
rules. It is a circle enclosing the declared maximum diversion distance from an Adequate airport.
The area enclosed within the circle is centred on the selected alternate airports, and the radius of
the circle is the declared maximum diversion distance. The 60 minutes radius circles will be within
this Area of operations circle.
So, to simplify, whenever a MAX diversion time(120 minutes) circles overlap each other, the route
can be planned using any airways enclosed in those circles, and this is an EDTO area of operations.
And inside these max diversion time or EDTO area of operation circles, there will be a 60 minutes
alternate circles along the route. At any point these 60 minutes circles does not over lap each
other, that segment is called an EDTO segment, where EDTO rules apply.
EDTO AREA
OF OPERATIONS
EDTO segment
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!2
B737-800
EDTO BASICS & PROCEDURES
EDTO TERMS AND DEFINITIONS
Maximum Diversion Time
The maximum diversion time of (120, 180, or 207 minutes) from an en- route alternate airport is
granted by the Department of Civil Aviation Malaysia. It is only used for determining the area of
operation and therefore is not an operational time limitation for conducting a diversion, which has
to cope with the prevailing weather conditions.
Maximum Diversion Distance
The maximum diversion distance is the distance covered in still air and ISA (or delta ISA) conditions
within the maximum diversion time at the selected one engine- out diversion speed schedule and
at the associated cruise altitude (including the descent from the initial cruise altitude to the
diversion cruise altitude). It is used for dimensioning the area of operations.
EDTO Area of Operations
The EDTO area of operations is the area in which it is authorised to conduct a flight under EDTO
regulations and is defined by the maximum diversion distance from an adequate airport or set of
adequate airports. It is represented by circles centred on the adequate airports, the radius of which
is the defined maximum diversion distance.
EDTO Entry Point (EEP)
The EDTO Entry Point is the point located on the aircraft’s outbound route at one hour flying time,
at the selected one-engine-out diversion speed schedule (in still air and ISA conditions), from the
last adequate airport prior to entering the EDTO segment. It marks the beginning of the EDTO
segment.
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!3
EDTO BASICS & PROCEDURES
B737-800
EDTO Segment
The EDTO segment starts at the EEP and finishes at EXP, and that is when the route is back and
remains within the 60 minutes area from an adequate airport. An EDTO route can contain several
successes of EDTO segments.
Equitime Point (ETP)
An Equitime Point is a point on the aircraft planned route of which the time it takes to go to both
en-route alternates are equally the same. The ETP position can be determined using a
computerised flight planning or geographically on a navigation or plotting chart.
The EDTO Exit Point (EXP)
The EDTO Exit Point (EXP) is the point located on the aircraft’s route, where the
aircraft has been flying in an EDTO segment, it enters an area of one hour flying
time, at the selected one-engine out diversion speed schedule (in still air and ISA
condition), to an Adequate airport. It marks the end of that particular EDTO
segment.
EDTO ALTERNATE RE-NOMINATION
At certain times, your en-route alternate requires renomination if the alternate itself suddenly
becomes unsuitable, due to weather, Notams, Closure etc. Usually a renomination is something
that you need to do if those things happen after the flight has departed the origin. Choosing a new
alternate airport can be achieved by checking the EDTO Area of Operations chart, and determining
the new EDP and ETP can be achieved by using the onboard FMC.
The easiest way to understand the Re-nomination concept is just by using the Isosceles Triangle
theory. An isosceles triangle is a triangle with (at least) two equal sides. In the figure below, the two
equal sides have length y and the remaining side has length x. The xC dotted line is a line
originating from the base line (AB), that divides the figure into 2 identical triangles. It does not
matter what the length of xC, both y will always be in equal value, provided the angle of the xC line
is 90º to the AB line.
So by using this geometrical theory, we can apply
it into our alternate EDP and ETP determination
process. To make things clear, in our terms:
A = En-route Alternate 1 (EA1)
B = En-route Alternate 2 (EA2)
AB = A direct track line from EA1 to EA2
x = Halfway point of EA1 to EA2.
xC = 90º Track plotted to intercept the flight plan
route, originating from the halfway point of the direct
track from EA1 to EA2.
C = The planned route Equidistance Point (EDP)
y = Distance between EDP to EA1/EA2
AC=BC
So this is the basic idea of the technique used to determine the EDP and ETP for the new renominated alternates. The method in laying this concept using the FMC will be discussed in the
next part.
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!4
EDTO BASICS & PROCEDURES
B737-800
The Control Display Unit (CDU)
LEFT
LINE
SELECT
KEYS
RIGHT
LINE
SELECT
KEYS
1L
1R
2L
2R
3L
3R
4L
4R
5L
5R
6L
6R
SCRATCHPAD
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!5
EDTO BASICS & PROCEDURES
B737-800
EDTO FMC WORKFLOW
EDTO Alternate Renomination
There are various ways or techniques when it comes to the FMC works in the EDTO alternate
renomination. One of them will be shown in the examples later. The first few steps are as follows:
STEP
STEP1:1:
CHECK
CHECKWEATHER
WEATHER
AND
ANDNOTAMS
NOTAMSTOTODETERMINE
DETERMINE
AERODROME
AERODROMESUITABILITY
SUITABILITY
STEP
STEP2:2:
CREATE
CREATEAN
AN
EQUIDISTANT
EQUIDISTANT
POINT
POINT(EDP)
(EDP)
STEP
STEP3:3:
CREATE
CREATEEQUITIME
EQUITIME
POINT
(ETP)
USING
POINT
(ETP)
USING
THE
THEEQUIDISTANT
EQUIDISTANTPOINT
POINT(EDP)
(EDP)
STEP
STEP4:4:
CHECK
CHECKCRITICAL
CRITICALFUEL
FUEL
USING
USINGTHE
THEFMC
FMC
STEP
STEP5:5:
CHECK
CHECKCRITICAL
CRITICALFUEL
FUEL
USING
USINGTHE
THECHART
CHART
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!6
EDTO BASICS & PROCEDURES
B737-800
STEP 1: AERODROME SUITABILITY
Weather and Notams determine an aerodrome’s suitability. Check the latest weather using all
means of communications practicable. ACARS can be used if available. When the weather report is
ready, nominated adequate alternate will become suitable. In this example, we will be using Phuket
(VTSP) and Chennai (VOMM) as our renominated alternates, and our route is from WMKK to VOMM.
STEP 2: CREATE AN EQUAL DISTANCE POINT (EDP)
An EDP can be created using the LEGS page of the CDU. The workflow basically is to determine an
equal distance between 2 points, by noting the Track and Distance that the LEGS page can display.
And for this instance, the 2 points are the airports selected to be used as an alternate. Here is how
you do it.
1. Open up the LEGS page by pressing the
button
2. Navigate to the last page of the LEGS page.
3. Type in the ICAO Aerodrome code of the first suitable alternate on the last available line on that
page. For this example, we will be using Phuket (VTSP) as our first En-Route Alternate (EA1).
4. Type in the second suitable En-Route Alternate (EA2) below the EA1. Chennai (VOMM) will be
our EA2 for this example. DO NOT EXECUTE (Fig. 1).
FIG. 1
FIG. 2
5. Note down the Track and the Distance displayed. (Highlighted in green ONLY FOR THIS
EXAMPLE). So in this case, our VTSP-VOMM direct track will be 286º and the track distance is
1109 NM. (Fig. 1) REMEMBER TO NOTE DOWN BOTH FIGURES.
6. Next, we need to calculate an EDP based on the VTSP-VOMM direct track. So theoretically, an
EDP should sit right on the halfway point of the VTSP-VOMM direct track. For that, we can take
the distance between those two alternate airports i.e. 1109 NM, and divide it in half. The
resulting figure will be 554 NM. So the 554 NM point on the VTSP-VOMM direct track is the EDP
of that track alone.
7. Now with this information, we need to mark it on the ND by using a User-created waypoint.
8. So using the On-Course Displacement technique, key in “VOMM/-554” onto the scratchpad.
Make this entry as a Waypoint by placing it between VTSP and VOMM. For this example, the key
we should be pressing is the 3L key (highlighted in green in (Fig. 2)). A new waypoint will be
created under the name “VOM01”. (Fig. 3)
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!7
EDTO BASICS & PROCEDURES
B737-800
FIG. 3
FIG. 4
9. Line Select “VOM01” and open up the FIX page (Fig. 4). (To open up a FIX page, press
)
10. Place “VOM01” into the blank boxes by pressing 1L (highlighted in green in Fig. 4), and VOM01
will be displayed as a fix, together with it’s Radial/Distance from info. (Fig. 6)
11. Erase the VTSP and VOMM waypoints on the LEGS page once you have transferred “VOM01” to
the FIX page.
FIG. 5
12. Back to the FIX page, you are now going to create a 90º radial line from the VTSP-VOMM track.
The line will originate from VOM01, and it will extend to the point it intercepts your planned
route track.(Fig. 5)
13. Depending on where your track is located relative to this fix (VOM01), you need to add/subtract
90º from the alternate direct track that you have noted down earlier. In this case, the track was
286º, so to get the 90º intercepting radial from the fix, verify:
• If your flight planned route is on the LEFT side of this fix, you SUBTRACT 90º
• If your flight planned route is on the RIGHT side of this fix, you ADD 90º
In this example, the planned route is on the left side of the fix, so, it is going to be:
286º-90º = 196º
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!8
EDTO BASICS & PROCEDURES
B737-800
FIG. 6
FIG. 7
14. Key in 196 onto the scratchpad (Fig. 7), and place it in one of the available lines (by pressing 2L
or 3L or 4L key) in the FIX page of VOM01, for this example, we use 3L (Fig. 8) . This will create
196º radial line from VOM01 and will be displayed on the ND as a Green Dashed Line. (The line
is similar to the dashed line in Fig.5)
15. Also to note, after you have placed the “196” in one of the available lines, the Distance, ETA,
Distance to Go, and Altitude will be automatically available, and all of this information is based
on the 196º radial that you have just inserted. (Fig. 8)
FIG. 8
FIG. 9
16. Next, line select the 196º (3L), and you will notice all of it’s radial/distance information will be
copied onto the scratchpad. For ease of explanation and for this explanation only, lets call this
196 radial/distance, the 196º Info. (Fig. 9)
17. With this 196º Info, you have to turn it into a User-created waypoint. To do that, return back to
the LEGS page and place this 196º Info right where the VOM01 dashed lines intercepted your
route. To do that:
a) Identify the leg which the dashed lines intercepts.
b) Identify the the 2 waypoints of that particular the leg.
c) Place the 196º Info between those 2 identified waypoints.
18. From there, a waypoint named “VOM02” will be created. VOM02 is your planned route EDP.
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!9
EDTO BASICS & PROCEDURES
B737-800
STEP 3: CREATE AN EQUAL TIME POINT (ETP)
In theory, an ETP should be the same as an EDP if there is no wind. Most of the time, wind factors
will cause some deviations, hence we need to determine an ETP to make our calculations more
accurate. So from the works that we have done so far, we have managed to calculate, and plot the
EDP, and reflect it onto our planned route. Now, based on that EDP, we are going to convert it into
an ETP. Here are the instructions:
1. Firstly we need to adjust the EDP to get the ETP. ETP is the point where it will take equivalent
time to go to the 2 en-route alternates. In order to do that, we first need to ensure that the wind
data has been entered on the RTE DATA page that can be accessed via the LEGS page.
2. Once the wind has been verified, we need to cross check the time required to fly directly to our
alternate from our EDP. This step involves multiple switch-overs between the LEGS page, and
the RTE DATA page.
3. With our EDP already been plotted, navigate to the page where VOM02 is located in the LEGS
page. (Fig. 10)
FIG. 10
FIG. 11
4. Key in the 4 letter ICAO code for your first alternate (EA1). In this case, it is Phuket, so key in
VTSP and place it right underneath VOM02. (Fig. 10) Again, DO NOT EXECUTE.
5. Next, press the RTE DATA prompt(6R key, can be seen in (Fig. 10)), and check the estimated
time that you will arrive at EA1 (highlighted in green only for this example), and note it down,
and press the ERASE prompt(6L) to clear the executable entry. (Fig. 11)
6. Repeat steps 4 & 5 to get the estimated time of arrival (ETA) for your second en-route alternate
(EA2).
7. Once done, verify and note the time difference between those two ETA of the alternates. If there
is none, then your EDP is your ETP.
8. If there is a difference, then use this formula:
Formula Explanation:
Δ time is the time difference. The reason we divide it by 2, is
based on the math rule of mean or average. Another way of
doing it is to total up ETA1 with ETA2, then divide it by 2. But
that is more time consuming.
As for the 8, it is just basically a miles per minute figure from
the aircraft’s average TAS. In this case, the average TAS is 480
Kt. So divide it by 60, you’ll get 8 NM/minute.
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!10
EDTO BASICS & PROCEDURES
B737-800
9. The unit for the “difference in time” will be in Minutes, and the figure that you will get from this
derivation will be in Nautical Miles.
10. For example, if we get a time difference of 3 minutes between the alternates’ ETA, so using the
formula, we will calculate it as :
11. So from the calculation, we got 12 NM. This is the number of miles we need to displace along
the planned route track in order to get an equivalent ETA from the EDP to the alternates.
12. As for which direction you want to shift the EDP, the rule is always to displace the EDP into the
direction where the wind is blowing from. In this example, lets assume we have a wind blowing
from 106º at 45 Kt. Our planned route is heading westerly. So we roughly have about 45 Kt of
tailwind. With this, we need to shift our waypoint VOM02,12 NM backwards. In other words, we
put the waypoint INTO THE WIND.
FIG. 12
FIG. 13
13. Same as previous, use the On-Track Displacement technique to move the EDP into the wind. So
if it were a tailwind, we will key in VOM02/-12 onto the scratchpad (Fig. 12). If it is a headwind,
we will key in VOM02/12, and place it in sequence before/after the EDP(VOM02) in the LEGS
page. A new waypoint with the name VOM03 will be created (Fig. 13) (highlighted in green only
for this example). You may now, delete VOM02.
14. From here, repeat the same steps as you have done in step 4 & step 5, only this time you place
the alternate underneath the new waypoint, VOM03. The resulting ETA of both alternates
should be the same, and this waypoint VOM03 is your ETP.
15. If the ETA still does not match, just do a minor 1 or 2 miles On-track Displacement accordingly.
As a side-note, do remember that if you are going to use any DATALINK or CPDLC service, do
transfer your ETP (VOM03) into the FIX page, as only published waypoints are to be displayed in
the LEGS page. And that is how you find and create an ETP.
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!11
EDTO BASICS & PROCEDURES
B737-800
STEP 4: CRITICAL FUEL VERIFICATION USING THE FMC
If a situation arise where fuel is critical, you may use the FMC to crosscheck your estimated
amount of fuel that you will still have once you diverted to the en-route alternate. This method of
analysing fuel is quick and have a fair amount of accuracy too. Also do be careful NOT TO
accidentally hit the “EXECUTE” button while you are doing this work, as this practice involves using
the PROGRESS page. Note that the PROGRESS and EXECUTE buttons are side by side. So do not
rush, and do this carefully. In general, the pages involves in this method is RTE, VNAV, LEGS and
PROGRESS. So lets get started.
1. The first step is to navigate to the ROUTE section, and you can do that by pressing
cycle to page 1, where you can see the “origin” and “destination” is located at.
and
2. Key in the ICAO 4 letter code for your chosen En-route alternate. Lets say we go for EA1, and
that is VTSP. So we type, VTSP at the “Dest” boxes. (Fig. 14) This action will remove your
destination and it’s STAR. Also always remember, DO NOT EXECUTE!
FIG. 14
FIG. 15
3. Next, navigate to the VNAV page by pressing
(NOTE: VNAV button only available on FANS
CDU. For CDU and MCDU, press the CRZ or DES button) Choose the CRUISE page, and over here,
change the speed to your selected strategy speed (Standard/Fixed speed is explained in detail
in OM-B Chapter 1, Page 1-6, Paragraph 1.1.2). If fuel is critical, then standard strategy should
be used, and the speed is M0.79/280 Kt. So change your cruise speed to 280 Kt.
4. Following the cruise modification, you then need to modify your DESCENT page in the VNAV
section. Select 280 Kt as your descent speed, and delete the 10 000 ft speed restriction.(Fig. 15)
(Highlighted in green only for this example)
5. Now, your cruise and descent profile for your VNAV based on this strategy has been set.
6. Next, you need to modify your waypoints, and it’s respective speed and height restrictions. To do
that, open the LEGS page by pressing the
button.
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!12
B737-800
EDTO BASICS & PROCEDURES
7. Find your ETP (VOM03), and key in 280/10000 in the SPD/ALT section, to simulate a
decompression scenario.(Fig. 16)(Highlighted in green only for this example)
FIG. 16
8. After you have done that, key in “VTSP” and place it in the last line of the legs page. Line select
“VTSP”, and place it right underneath your ETP (VOM03). (Fig. 17) Do make sure VTSP is the
last waypoint in your legs page. Now modify the SPD/ALT for VTSP, by keying in
“/1500”. This will create a hard altitude constraint of 1500’ above VTSP.(Fig. 17) (Highlighted in
green only for this example)
FIG. 17
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!13
B737-800
EDTO BASICS & PROCEDURES
9. You are almost complete. But for an even better fuel forecast, you may create another point
between your ETP and VTSP. By creating this point, the FMC will do it’s calculation based on a
slant path rather than a rapid altitude change from 10 000 ft(ETP) to 1500 ft(VTSP). To create
this point, all you have to do is displace your ETP 50 miles ahead, using the On-Course
Displacement technique. So Key in VOM03/50, and place it right after VOM03. VOM04 will be
created, and you can straight away see the crossing altitude of VOM04 will be about 9000+ ft.
(Fig. 18) (Highlighted in green only for this example)
FIG. 18
. Check the estimated fuel
10. Once all is done, navigate to the PROGRESS page by pressing
that you will have in VTSP, and make sure it is more than 2400 kg. (Fig. 19) (Highlighted in
green only for this example)
FIG. 19
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!14
B737-800
EDTO BASICS & PROCEDURES
STEP 5: CRITICAL FUEL VERIFICATION USING THE OPS INFO CHART
Using the chart in the OPS INFO section of the QRH for critical fuel determination is pretty much
straight forward.
1. Firstly, check the QRH in the OPS INFO section, for the engine inoperative critical fuel reserve.
2. You also need to get the estimate weight over the new ETP by using the OFP or (the current fuel
onboard minus the anticipated fuel burn) + ZFW.
3. Enter the chart with distance from ETP to the alternate together with the anticipated wind.Do
the necessary adjustment to the fuel as required in the chart.
4. Ensure fuel onboard at the new ETP(VOM03) is equal to or higher than the critical fuel required.
5. If It is less, ensure arrival fuel is more than the minimum diversion fuel (MDF).
B737-800/EDTO/FMCWORKS/JAZMIHISYAM/2018
!15