Journal of Airport Engineering Technology (JAET) https://e-journal.
id/index.
php/jaet Volume: 6.
No.
June, 2026: pp.
E-ISSN.
P-ISSN: 2774-9622.
DOI: 10.
52989/jaet.
Submitted: 2026-03-25.
Revised: 2026-05-02.
Accepted: 2026-06-03
FLIGHT LEVEL DETERMINATION: CRUISE ALTITUDE ON
FUEL CONSUMPTION FOR AIRBUS A320CEO
Audry Farisqi Mosyam1.
Hafiz Ardian2 Kuala Pembuang Airport.
Kalimantan Tengah.
Indonesia Airport Management Study Programme.
Politeknik Penerbangan Palembang.
Indonesia *Correspondence e-mail: mosyam.
audry@gmail.
Abstract Fuel efficiency is a critical issue in low-cost carrier operations, particularly on the mediumrange Jakarta-Ambon route with high strategic value and load factors.
This study evaluates the alignment between flight levels (FL) selected by dispatchers and the optimum FL based on aircraft weight, compares actual fuel consumption with Quick Determination (QDT) simulation results, and analyses how aircraft weight influences fuel efficiency.
A descriptive qualitative approach was employed using document analysis, direct observation at the Operation Control Center (OCC), and in-depth interviews with three licensed flight Thirty actual Airbus A320 CEO flight plans for PT.
Citilink Indonesia on the Jakarta-Ambon route in November 2024 were analyzed.
Results indicate that 76.
6% of actual FLs did not match the calculated optimum FL, yielding a fuel penalty of 500-1,558 kg per flight, with an average of approximately 900 kg per deviating flight.
Implementing the QDT method enables more precise FL planning based on aircraft weight, contributing to measurable gains in operational fuel efficiency.
Keywords: airbus A320CEO, flight level, fuel consumption, operational efficiency, quick Copyright for Authors A 2025 Audry Farisqi Mosyam.
Hafiz Ardian Flight Level Determination: Cruise Altitude on Fuel Consumption for Airbus A320CEO Introduction Fuel efficiency is a vital element in the modern aviation industry, not only as a means of reducing operational costs, but also as part of a global strategy to reduce carbon emissions and support environmental In an intensely competitive continuously seek ways to optimize flight operations, especially on medium and longhaul routes where efficiency margins are thin.
For low-cost carriers (LCC.
such as PT.
Citilink Indonesia, every kilogram of fuel saved directly impacts profitability and One of the most critical technical aspects of flight efficiency is determining cruise altitude, or Flight Level (FL).
A non-optimal FL results in a fuel penalty, excess fuel consumption due to a mismatch between atmospheric conditions and aircraft performance (Mukhina & Ilnytska, 2.
It is demonstrated that both cruise speed and FL changes can significantly affect fuel consumption patterns in air traffic flow management (De Lemos & Woodward.
Therefore, selecting the appropriate FL is a strategic factor that profoundly determines flight efficiency (Keyeci et al.
Aircraft conditions, and route characteristics are among the primary factors influencing the selection of optimum cruise altitude (Jafarimoghaddam & Soler, 2.
Recent demonstrated that the optimal cruise altitude can minimize fuel consumption while improving aircraft operational performance during the climb and cruise phases (Kang & Ryu, 2.
The Jakarta-Ambon route (CGKAMQ), covering approximately 1,389 Nautical Miles, falls into the medium-range category and traverses oceanic and mountainous airspace.
Secondary data from Citilink flight plans indicate an average of 141 passengers and a payload of approximately 13,500 kg per flight, reflecting a consistently high load factor.
This economic significance makes fuel efficiency on this route a priority concern.
selection is governed by multiple regulatory CASR 121.
95 requires FL to be determined based on flight direction .
dd/even FL rul.
and accounts for air traffic, weather, and ATC instructions.
ICAO Annex 6.
Articles 4.
1 and 4.
5, mandates that operators select an FL that complies with altitude rules and is optimal for fuel Article 3.
3 governs the application of the Reduced Vertical Separation Minimum (RVSM), enabling 1,000-foot intervals between FL290 and FL410 and providing greater flexibility for optimal FL selection.
In addition.
Annex 2 document establishes the standardized flight level allocation system for Instrument Flight Rules operations, ensuring vertical separation and safe aircraft movement while supporting efficient airspace utilization.
Compliance with these provisions forms the basis for flight level planning in commercial airline However, achieving the optimum flight level is not always possible because Operational airspace constraints frequently prevent aircraft from maintaining fuel-optimal trajectories, resulting in increased fuel consumption, and reduced operational efficiency (Huang & Cheng.
In practice.
FL selection is often based on dispatcher experience and standard systematically referencing the theoretically optimum FL derived from aircraft weight and atmospheric variables (Chukundah et al.
The FCOM Quick Determination (QDT) method offers a precise, weight-based approach for estimating fuel requirements at different FLs.
Recent studies have shown that trajectory and cruise altitude optimization can significantly improve fuel efficiency and operational performance by reducing unnecessary fuel burn during flight operations (Huang & Cheng, 2.
Accurate fuel estimation is increasingly recognized as a key component of sustainable airline operations because it enables operators to minimize unnecessary fuel loading, reduce operational costs, and lower carbon emissions while maintaining required safety margins (Li et al.
This study therefore aims to: .
Vol 6 No 2 .
evaluate whether dispatcher-selected FLs correspond to the weight-based optimum FL derived from FCOM data.
quantify the fuel penalty resulting from FL deviations across 30 actual November 2024 flight plans on the CGK-AMQ route.
Previous studies using Airbus A320 operational data have shown that aircraft weight characteristics and flight-planning parameters significantly influence trip fuel requirements, underscoring the importance of accurate fuel planning for improving operational efficiency (Ashar.
FCOM Cruise Mach 0.
78 ISA 15 Optimum Level Chart, based on each flight's ETOW.
Second, trip fuel at the optimum FL was simulated using the QDT method incorporating the following calculations:
ISA = 15 (FL/1.
y (Oe.
iISA = OAT Oe ISA Correction Weight = (Est.
Landing Weight Oe Ref.
Landing Weigh.
/ 1,000 y Correction Factor Correction ISA = 0.
015 y iISA y Air Distance (NM) Final Trip Fuel = Table Fuel Correction Weight Correction ISA Third, actual trip fuel from flight plans was compared against QDT simulation The Outside Air Temperature (OAT) values used in the QDT calculations were obtained from the actual flight plan weather data generated through the operational flight planning system.
These OAT values represent the forecast temperature at the planned cruise altitude and were used to calculate ISA deviation .
ISA) (Kuprikov, 2.
, which serves as a correction factor in estimating trip fuel requirements.
The difference was recorded as fuel penalty.
Interview findings were used to triangulate and contextualize the quantitative results through qualitative content analysis (Sugiyono, 2.
Methods This study employed a descriptive qualitative approach to analyze the relationship between FL selection and fuel consumption on the CGK-AMQ route operated by PT.
Citilink Indonesia using Airbus A320CEO aircraft.
According to Sugiyono .
, qualitative descriptive research enables a comprehensive explanation of the operational context, including the dynamics of FL selection and the influence of variables such as Dry Operating Weight (DOW) and payload.
Data were collected through three complementary techniques.
First, document analysis of 30 actual flight plans (Dispatch Release, flight CTV-.
from the period 1-30 November 2024, supplemented by the FCOM A320 2019.
CASR regulations, and PT.
Citilink OM-A Second, direct observation at the OCC and Flight Operations (FLOPS) of PT.
Citilink Indonesia during the OJT period in November 2024.
Third, semi-structured indepth interviews with three licensed Flight Operation Officers (FOO) who directly handle the CGK-AMQ route.
The population comprises all 30 PT.
Citilink Indonesia CGK-AMQ flights during November 2024.
All 30 flight plans were included using purposive sampling to ensure comprehensive monthly coverage.
The primary variables are FL .
ndependent operationalized as trip fuel in kilograms .
ependent variabl.
Data analysis followed three sequential stages.
First, the optimum FL for each flight was determined from the Results And Discussions General Overview and Flight Plan Data Observations were focused on the CGK-AMQ operational route served by PT.
Citilink Indonesia using Airbus A320CEO The significance of the JakartaAe Ambon route also aligns with the concept of Indonesia ministry of transportation-aviation plan, which defines air routes as designated pathways connecting airports to support national connectivity, economic activity, and regional development.
Therefore, improving fuel efficiency on this route contributes not only to airline operational performance but also to broader transportation objectives.
This route covers approximately 1,389 NM, traversing two flight information regions: FIR Wi (Jakart.
and FIR Wa (Makassa.
, with an average flight time of 3 hours 11 minutes under normal weather conditions.
Audry Farisqi Mosyam.
Hafiz Ardian Flight Level Determination: Cruise Altitude on Fuel Consumption for Airbus A320CEO selection on this route typically ranges from FL330 to FL350, depending on operational FL determination and fuel planning at Citilink are performed by the Flight Dispatcher (Control Flight Dispatch/CFD) within the Operation Control Center (OCC).
Dispatchers use the NavBlue system, integrated with FCOM data and realtime weather data.
Although digital systems are the primary planning tool, the QDT method remains in use for training, validation, and contingency scenarios.
Table 1 presents the full dataset of 30 actual flight plans analyzed in this study.
Table 1.
Actual Flight Plan Data - CGKAMQ Route.
November 2024
Date
A/C
Reg.
ETOW
71,541 Block
Fuel
14,641 Trip
Fuel
8,731 Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
PKGQR
PKGLV
73,264
14,438
8,985
PKGLT
73,002
13,489
8,990
PKGQL
72,541
13,850
8,734
PKGQU
69,042
15,404
8,479
PKGLM
71,883
16,375
9,475
PKGLT
71,772
17,948
9,217
PKGLW
73,391
15,574
9,402
PKGQG
72,109
13,310
8,956
PKGQG
72,668
14,111
8,984
PKGLG
72,803
17,186
8,771
PKGTE*
72,410
14,478
7,768
PK330 72,135
15,187
Nov
GLO
PK330 71,448
16,554
Nov
GLV
PK330 70,926
16,680
Nov
GLM
PK330 71,970
16,772
Nov
GLL
PK330 72,282
17,957
Nov
GQH
PK330 72,114
17,943
Nov
GQU
PK330 72,757
16,133
Nov
GQP
PK330 70,689
12,725
Nov
GLG
PK330 69,982
16,704
Nov
GLT
PK330 72,775
17,311
Nov
GLO
PK330 73,381
15,281
Nov
GQT
PK350 71,480
13,909
Nov
GTD
PK350 71,433
14,426
Nov GTE* PK350 69,472 17,396 Nov
GLO
PK350 69,009
16,053
Nov
GQL
PK350 67,565
15,960
Nov
GQS
PK330 71,799
18,185
Nov
GQA
PK330 70,738
15,020
Nov
GQK
Note: * indicates Airbus A320NEO aircraft.
9,472
9,241
9,348
9,273
8,952
8,848
8,894
8,446
9,001
9,492
9,152
7,676
7,677
9,141
8,795
8,786
9,247
9,101
The data show that 23 out of 30 flights .
7%) were planned at FL330, while 7 flights .
3%) were planned at FL350.
Vol 6 No 2 .
ETOW values ranged from 67,565 to 73,391 kg, reflecting the variation in daily payload and aircraft configuration.
Actual block fuel ranged from 12,725 to 18,185 kg, and trip fuel from 7,676 to 9,492 kg, indicating substantial day-to-day operational variation.
Optimum FL Determination and QDT Simulation Optimum FL for each flight was determined by referencing the FCOM Cruise Mach 0.
78 ISA 15 Level Chart, which maps ETOW to the corresponding optimum Based on the ETOW distribution of this study .
,565-73,391 k.
, the chart consistently yields an optimum FL of 350 for all 30 flights.
This is consistent with the FCOM recommendation and findings, which note that medium-range narrow-body aircraft achieve best aerodynamic efficiency at higher cruise levels when weight permits.
Following the determination of the optimum FL, a QDT simulation was performed for each flight to estimate the trip fuel at FL350.
The calculation incorporates ISA correction and weight correction to account for actual atmospheric and weight Table 2 presents a complete worked example for the 13 November 2024 flight (PK-GLO.
ETOW = 72,135 k.
, which exhibited the most representative calculation Table 2.
QDT Calculation Example - Flight 13 November 2024 (PK-GLO.
FL.
Parameter DOW Payload Zero Fuel Weight (ZFW) Holding Fuel .
Landing Weight at Alternate Alternate Fuel .
able Landing Weight at Destination Trip Fuel .
able value at FL.
Contingency Fuel .
% y Tri.
Extra Fuel Estimated TOW Taxi Fuel .
min y 11.
RAMP Weight Correction Weight [.
,189Oe55,.
/1,000 y Correction ISA .
015 y 12 y 1,402 NM] Final Trip Fuel .
,710 338 .
Final Block Fuel 338 kg 253 kg 8,301 kg 13,469 kg The QDT procedure begins by establishing the ZFW from DOW and payload, then sequentially adds holding fuel, alternate fuel, trip fuel .
rom FCOM tabl.
, contingency fuel, and extra fuel to derive ETOW, and finally adds taxi fuel for the RAMP weight.
Corrections for ISA deviation .
ISA = 12AC) and weight deviation from the reference landing weight produce a final trip fuel estimate of 8,301 kg, significantly lower than the 9,472 kg recorded in the actual flight plan at FL330, yielding a fuel penalty of 1,171 This calculation methodology was applied uniformly across all 30 flights, using routespecific parameters: air distance of 1,3461,402 NM .
arying by filed routin.
ISA deviations based on recorded OAT values, and aircraft-specific DOW data from the Citilink 2023 Weight & Balance Manual.
Flight Level Deviation and Fuel Penalty Analysis Table 3 presents a complete comparison of actual FL and optimum FL for all 30 flights, including the computed fuel penalty for each observation.
Table 3.
FL Deviation and Fuel Penalty All 30 Flights (Bold = Penalty > 1,000 k.
Value 42,266 kg 14,305 kg 56,571 kg 1,119 kg 57,690 kg 2,499 kg 60,189 kg 7,710 kg 416 kg 2,000 kg 70,906 kg 253 kg 71,159 kg Date .
QDT Trip Fuel .
7,985 Pena .
Act.
Trip
Fuel
8,731 Nov
Nov
Nov
Nov
Nov
8,985
8,066
8,990
8,106
8,734
8,120
8,479
8,479
Audry Farisqi Mosyam.
Hafiz Ardian Flight Level Determination: Cruise Altitude on Fuel Consumption for Airbus A320CEO
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
Nov
9,475
8,139
1,336
9,217
7,976
1,241
9,402
8,291
1,111
8,956
8,408
8,984
8,373
8,771
8,265
7,768
7,768
9,472
8,301
1,171
9,241
8,122
1,119
9,348
8,028
1,320
9,273
8,097
1,176
8,952
7,979
8,848
7,942
8,894
8,078
8,446
8,120
9,001
7,928
1,073
9,492
7,934
1,558
9,152
8,340
7,676
7,676
7,677
7,677
69,4 35 350 9,141 9,141
Nov
69,0 35 350 8,795 8,795
Nov
67,5 35 350 8,786 8,786
Nov
71,7 33 350 9,247 8,352 895
Nov
70,7 33 350 9,101 8,389 712
Nov Note: * A320NEO aircraft .
xcluded from QDT penalty analysi.
Penalty = Actual Trip Fuel Oe QDT Trip Fuel.
The results reveal a clear and consistent Of the 30 flights, 23 .
6%) operated at an FL lower than the FCOM-recommended optimum, all using FL330 when FL350 was Not a single flight operated above its optimum FL.
The remaining 7 flights .
3%) coincidentally or intentionally operated at the exact optimum FL350.
Among the 23 deviating flights, fuel penalty ranged from 326 kg .
Novembe.
to 1,558 kg .
Novembe.
, with a mean penalty of approximately 900 kg per flight.
The highest penalties -- all exceeding 1,000 kg, occurred on 6, 7, 8, 13, 14, 15, and 16 November .
olded in Table .
These flights share a common characteristic: ETOW above 71,000 kg combined with FL330 selection.
This confirms the theoretical expectation that the penalty is most severe when the gap between actual and optimum performance conditions is Higher cruise altitudes generally yield lower aerodynamic efficiency, which is important for fuel optimization, as each aircraft has a specific Mach number and Flight Level combination that minimizes fuel burn during cruise operations (Poll & Schumann.
The relationship between ETOW and fuel penalty observed here is also consistent with recent aviation fuel prediction studies, which identified aircraft weight as one of the consumption during cruise operations (Lin et , 2.
, who demonstrated that aircraft Vol 6 No 2 .
weight strongly influences fuel consumption during both climb and cruise phases.
Aircraft weight remains one of the most consumption because fuel efficiency is strongly related to aircraft mass, payload characteristics, and operational loading Therefore, variations in ETOW can substantially influence fuel requirements even when aircraft type and route distance remain unchanged (Kyhn & Scholz, 2.
Recent studies have further emphasized that unnecessary aircraft weight directly increases fuel consumption and operational costs.
Accurate weight management, including optimizing take-off and zero-fuel weights, has been identified as one of the most practical strategies for improving fuel efficiency and reducing emissions in commercial aviation operations (Inan et al.
, 2.
This finding is also supported by recent fuel prediction research demonstrating that aircraft fuel consumption is determined by the interaction of multiple operational variables, including aircraft weight, flight profile, and environmental conditions, all of which contribute to variations in fuel burn during flight operations (Sertdemir et al.
, 2.
These environmental benefits are supported by studies demonstrating that additional flight operation time directly increases fuel Therefore, optimization that reduces unnecessary fuel burn contributes not only to cost savings but also to lower environmental impacts (Dhimas et al.
, 2.
Conversely, flights 5, 12, 24, 25, 26, 27, and 28 November recorded zero fuel penalty, confirming that QDT-based optimum FL selection can effectively eliminate excess fuel consumption under appropriate weight Notably, the three A320NEOoperated flights .
, 24, 25 Novembe.
also used FL350 and showed negligible difference, suggesting that the CEO fuel penalty disadvantage is primarily driven by FL choice rather than engine type alone.
Operational Insights from Flight Dispatcher Interviews To contextualize the quantitative findings, semi-structured interviews were conducted with three FOOs (Flight Dispatcher.
who actively manage the CGKAMQ route.
Table 4 summarizes the key themes and findings.
Table 4.
Summary of Flight Dispatcher Interview Findings Topic / Question Flight plan procedure for CGKAMQ route Primary authority in FL determination Frequency of FL changes from initial Most dominant factors in FL Effect of ETOW on FL selection Safety vs.
efficiency trade-off Impact of FL difference on fuel Key Findings from Informants All three informants confirmed that flight plans follow SOP Flight Dispatch, referencing Jeppesen Charts.
FCOM fuel calculations, and official DOW The process includes weather briefing.
NOTAM
ETP
payload and cargo analysis .
, lithium batteries, live Navigation team (JKT OF) determines the optimum FL using FCOM performance tables and inputs it to NavBlue.
The CFD/Dispatcher validates and adjusts up to 1 hour before departure based on actual Changes occur when PIC has specific preferences, weather imposes restrictions .
cing, turbulenc.
, or technical MEL limitations apply .
IDG
failure limiting maximum FL).
Tolerance is typically A2 FL levels from the planned FL.
All informants ranked: .
aircraft weight/ETOW, .
weather at altitude, .
ATC availability, .
MEL/technical aircraft status.
Fuel efficiency is considered but remains secondary to safety.
High ETOW limits achievable FL.
An overloaded aircraft cannot efficiently climb to FL370.
FL330-FL350
All informants FCOM performance tables are used as reference for this calculation.
Consensus: safety is the absolute priority.
FL optimum turbulence, icing, or high traffic exists at that altitude.
However, conditions, dispatchers always seek the lowest possible fuel burn within safe margins.
Estimated difference between FL330 and FL350: 200-1,000 kg depending on wind and Higher FL reduces drag, lowering fuel burn -- but only when aircraft weight permits it.
Forcing a very high FL with high ETOW can increase fuel burn due to engine overload.
Audry Farisqi Mosyam.
Hafiz Ardian Flight Level Determination: Cruise Altitude on Fuel Consumption for Airbus A320CEO The interviews provide important operational context for interpreting the FL deviation pattern identified in Table 3.
All three informants confirmed that ETOW and DOW are formally incorporated into FL planning, but they are not the sole Weather at cruising altitude .
urbulence, icin.
ATC slot congestion, aircraft MEL/technical limitations, and PIC preference frequently override the weightbased optimum.
One informant explicitly noted: "We can choose an FL that is slightly less efficient if the optimum FL has Safety is always the primary priority, not just fuel savingAy.
This explains why 76.
6% of flights operated below the theoretical optimum: the observed deviations represent deliberate operational adaptations rather than planning Recent operational optimization studies similarly report that aircraft frequently deviate from theoretically optimal flight profiles because of airspace constraints, traffic management requirements, and operational safety considerations, despite the resulting reduction in fuel efficiency (Zhu & Li, 2.
Previous studies have demonstrated that flight altitude selection involves a tradeoff between fuel consumption, flight time, and environmental impacts.
Consequently, operational decisions may intentionally deviate from fuel-optimal altitudes to satisfy broader operational or environmental objectives (Xue et al.
, 2.
The standard Citilink operational template for the eastbound CGK-AMQ route defaults to FL330, with FL350 or FL370 assigned when conditions and ETOW specifically permit.
This operational conservatism is consistent with findings by (Mukhina & Ilnytska, 2.
, who noted that practical FL decisions involve complex trade-offs between efficiency, safety margins, and ATM constraints that theoretical optimization models do not fully capture.
The informants also confirmed that fuel penalty from FL330 vs.
FL350 is recognized operationally, estimated at 200-1,000 kg depending on conditions, but is considered an acceptable cost when safety or operational constraints dictate the lower FL, even though this study's QDT-derived figures show penalties of up to 1,558 kg Ai notably higher than the operational estimate.
Recent studies have demonstrated that aircraft weight and balance parameters, including payload distribution and center of gravity position, significantly influence fuel consumption and operational efficiency.
Higher aircraft weight generally requires greater engine thrust, resulting in increased fuel burn during flight operations (Sertdemir et al.
, 2.
Further research demonstrated that payload variation, a key driver of ETOW in this study, significantly amplifies per-flight fuel consumption, making accurate FL selection even more critical when payloads are consistently high, as on the CGK-AMQ route (Setiawan et al.
, 2.
The QDT method proved accurate and consistent as a simulation Its reliance on FCOM tables with weight and ISA corrections renders it traceable, specialized software.
This study reinforces the case for integrating QDT validation into the standard dispatch workflow, particularly as a pre-dispatch check of automated system outputs for routes with consistent ETOW profiles, such as CGK-AMQ.
From an operational standpoint, the interviews indicate that the primary barrier to implementing the optimum FL is not dispatcher knowledge or system capability, but rather the conservative operational defaults embedded in the NavBlue template, and the precedence given to safety over efficiency when any uncertainty exists (Novita et al.
, 2.
Addressing this gap does not require abandoning conservative safety rather, it calls for a structured decision support mechanism that clearly signals when the safety-efficiency trade-off can be resolved in favor of the higher FL without compromising operational safety.
weight-based FL alert within the NavBlue interface -- flagging when an aircraft weight falls within the FL350 optimum range -- could serve this purpose with minimal operational Comparison with prior studies further contextualizes these findings.
Lazic et .
examined FL effects on sustainable aviation fuel efficiency, finding that optimal FL varies with aircraft weightAiconsistent Vol 6 No 2 .
FL350 recommendation for the observed ETOW This finding is consistent with recent studies identifying aircraft weight variables, including take-off weight and zero-fuel weight, as major determinants of fuel consumption during flight operations (Hassan et al.
, 2.
advisory module within existing NavBlue dispatch workflows is recommended as a practical implementation pathway.
References